Number analysis
49
49 is a composite odd number that factors as 7^2.
49 is a composite odd number that factors as 7^2.
The number itself
- Value
- 49
- Digits
- 2
- Digit sum
- 13
- Reversed
- 94
- Palindrome
- No
4 + 9
Digit sum repeated until one digit remains; equals n mod 9 (with 9 for multiples of 9).
Reverses to 94.
Parity and primality
- Parity
- Odd
- Prime
- No
- Squarefree
- No
- Semiprime
- Yes
- Prime power
- 7^2
- Powerful
- Yes
- Möbius μ(n)
- 0
- Nearest primes
- 47 ← → 53
Leaves remainder 1 on division by 2.
Composite — it factors as 7^2.
1 distinct prime factor, 2 with multiplicity.
At least one prime appears squared.
A product of exactly two primes, counted with multiplicity.
A single prime raised to a power.
Every prime factor appears at least squared.
Zero, because a squared prime divides n.
A gap of 6 between them.
Divisors
- Aliquot sum
- 8
- Classification
- Deficient
1, 7, 49
The proper divisors — everything except n itself.
Its proper divisors fall short by 41.
How many integers from 1 to n share no factor with n.
Sums and additive structure
- Sum of two squares
- Yes
- Sum of three squares
- Yes
- Sum of four squares
- Yes
0² + 7² = 49
Legendre's three-square theorem allows it.
Lagrange's four-square theorem: every non-negative integer is, without exception.
Shapes and sequences
- Square number
- Yes — the 7th
Digit curiosities
- Happy number
- Yes
- Harshad number
- No
- Collatz trajectory
- 24 steps to 1
Repeatedly summing the squares of its digits reaches 1.
Not divisible by its digit sum 13.
Peaks at 148 along the way.
Written other ways
- Binary
- 110001
- Octal
- 61
- Hexadecimal
- 31
- Base 36
- 1D
- Roman numerals
- XLIX
- In words
- forty-nine
- Scientific notation
- 4.9 × 10^1
Is 49 a prime number?
Composite — it factors as 7^2.
Nearby numbers
Other numeral systems
Beyond the bases and Roman numerals above, these notations write 49 their own way.
- Greek (alphabetic)
- ΜΘʹ
- Babylonian cuneiform
- 𒐏𒐝
- Tamil
- ௪௰௯
References
Further reading: Wikipedia · Wikidata
Notations, naming and the links above come from Wikidata, whose structured data is dedicated to the public domain under CC0-1.0. Retrieved 2026-10-07.