21456831 has 16 divisors (see below), whose sum is σ = 31409280. Its totient is φ = 12921120.

The previous prime is 21456829. The next prime is 21456859. The reversal of 21456831 is 13865412.

It is not a de Polignac number, because 21456831 - 2¹ = 21456829 is a prime.

It is a super-2 number, since 2×21456831² = 920791193125122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3385 + ... + 7373.

It is an arithmetic number, because the mean of its divisors is an integer number (1963080).

Almost surely, 2^21456831 is an apocalyptic number.

21456831 is a deficient number, since it is larger than the sum of its proper divisors (9952449).

21456831 is a wasteful number, since it uses less digits than its factorization.

21456831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4166.

The product of its digits is 5760, while the sum is 30.

The square root of 21456831 is about 4632.1518757485. The cubic root of 21456831 is about 277.8786584639.

The spelling of 21456831 in words is "twenty-one million, four hundred fifty-six thousand, eight hundred thirty-one".