2157831 has 12 divisors (see below), whose sum is σ = 3356808. Its totient is φ = 1327824.

The previous prime is 2157823. The next prime is 2157833. The reversal of 2157831 is 1387512.

It is not a de Polignac number, because 2157831 - 2³ = 2157823 is a prime.

It is a super-2 number, since 2×2157831² = 9312469249122, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 2157795 and 2157804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157833) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9105 + ... + 9338.

It is an arithmetic number, because the mean of its divisors is an integer number (279734).

2^2157831 is an apocalyptic number.

2157831 is a deficient number, since it is larger than the sum of its proper divisors (1198977).

2157831 is a wasteful number, since it uses less digits than its factorization.

2157831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18462 (or 18459 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 2157831 is about 1468.9557515460. The cubic root of 2157831 is about 129.2227986810. Note that the first 3 decimals are identical.

It can be divided in two parts, 21578 and 31, that added together give a square (21609 = 147²).

The spelling of 2157831 in words is "two million, one hundred fifty-seven thousand, eight hundred thirty-one".