21831472 has 20 divisors (see below), whose sum is σ = 45552640. Its totient is φ = 10075968.

The previous prime is 21831449. The next prime is 21831493. The reversal of 21831472 is 27413812.

It is a super-2 number, since 2×21831472² = 953226339373568, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21831472.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52272 + ... + 52687.

It is an arithmetic number, because the mean of its divisors is an integer number (2277632).

Almost surely, 2^21831472 is an apocalyptic number.

It is an amenable number.

21831472 is an abundant number, since it is smaller than the sum of its proper divisors (23721168).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21831472 is a wasteful number, since it uses less digits than its factorization.

21831472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104980 (or 104974 counting only the distinct ones).

The product of its digits is 2688, while the sum is 28.

The square root of 21831472 is about 4672.4160773630. The cubic root of 21831472 is about 279.4866102778.

It can be divided in two parts, 2183 and 1472, that added together give a triangular number (3655 = T₈₅).

The spelling of 21831472 in words is "twenty-one million, eight hundred thirty-one thousand, four hundred seventy-two".