2157931 has 4 divisors (see below), whose sum is σ = 2167200. Its totient is φ = 2148664.

The previous prime is 2157923. The next prime is 2157989. The reversal of 2157931 is 1397512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2157931 - 2³ = 2157923 is a prime.

It is a super-2 number, since 2×2157931² = 9313332401522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2157931.

It is not an unprimeable number, because it can be changed into a prime (2157901) 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, 4276 + ... + 4753.

It is an arithmetic number, because the mean of its divisors is an integer number (541800).

2^2157931 is an apocalyptic number.

2157931 is a deficient number, since it is larger than the sum of its proper divisors (9269).

2157931 is an equidigital number, since it uses as much as digits as its factorization.

2157931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9268.

The product of its digits is 1890, while the sum is 28.

The square root of 2157931 is about 1468.9897889366. The cubic root of 2157931 is about 129.2247948336.

The spelling of 2157931 in words is "two million, one hundred fifty-seven thousand, nine hundred thirty-one".