21331056 has 40 divisors (see below), whose sum is σ = 58348944. Its totient is φ = 6691840.

The previous prime is 21331049. The next prime is 21331067. The reversal of 21331056 is 65013312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12255 + ... + 13886.

Almost surely, 2^21331056 is an apocalyptic number.

It is an amenable number.

21331056 is an abundant number, since it is smaller than the sum of its proper divisors (37017888).

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

21331056 is a wasteful number, since it uses less digits than its factorization.

21331056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26169 (or 26163 counting only the distinct ones).

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21331056 is about 4618.5556183725. Note that the first 3 decimals coincide. The cubic root of 21331056 is about 277.3346405469.

Adding to 21331056 its reverse (65013312), we get a palindrome (86344368).

The spelling of 21331056 in words is "twenty-one million, three hundred thirty-one thousand, fifty-six".