21631056 has 40 divisors (see below), whose sum is σ = 57686784. Its totient is φ = 6977280.

The previous prime is 21631039. The next prime is 21631061. The reversal of 21631056 is 65013612.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5781 + ... + 8756.

Almost surely, 2^21631056 is an apocalyptic number.

21631056 is the 2942-nd centered pentagonal number.

It is an amenable number.

21631056 is an abundant number, since it is smaller than the sum of its proper divisors (36055728).

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

21631056 is a wasteful number, since it uses less digits than its factorization.

21631056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14579 (or 14573 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21631056 is about 4650.9199090072. The cubic root of 21631056 is about 278.6287375659.

Adding to 21631056 its reverse (65013612), we get a palindrome (86644668).

The spelling of 21631056 in words is "twenty-one million, six hundred thirty-one thousand, fifty-six".