31157 has 4 divisors (see below), whose sum is σ = 35616. Its totient is φ = 26700.

The previous prime is 31153. The next prime is 31159. The reversal of 31157 is 75113.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75113 = 31 ⋅2423.

It is a cyclic number.

It is not a de Polignac number, because 31157 - 2² = 31153 is a prime.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2219 + ... + 2232.

It is an arithmetic number, because the mean of its divisors is an integer number (8904).

2³¹¹⁵⁷ is an apocalyptic number.

It is an amenable number.

31157 is a deficient number, since it is larger than the sum of its proper divisors (4459).

31157 is an equidigital number, since it uses as much as digits as its factorization.

31157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4458.

The product of its digits is 105, while the sum is 17.

The square root of 31157 is about 176.5134555778. The cubic root of 31157 is about 31.4667491579.

Subtracting 31157 from its reverse (75113), we obtain a triangular number (43956 = T₂₉₆).

The spelling of 31157 in words is "thirty-one thousand, one hundred fifty-seven".