21331256 has 16 divisors (see below), whose sum is σ = 40188840. Its totient is φ = 10614240.

The previous prime is 21331217. The next prime is 21331267. The reversal of 21331256 is 65213312.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4631 + ... + 8006.

Almost surely, 2^21331256 is an apocalyptic number.

It is an amenable number.

21331256 is a deficient number, since it is larger than the sum of its proper divisors (18857584).

21331256 is a wasteful number, since it uses less digits than its factorization.

21331256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12854 (or 12850 counting only the distinct ones).

The product of its digits is 1080, while the sum is 23.

The square root of 21331256 is about 4618.5772701125. The cubic root of 21331256 is about 277.3355073075.

Adding to 21331256 its reverse (65213312), we get a palindrome (86544568).

The spelling of 21331256 in words is "twenty-one million, three hundred thirty-one thousand, two hundred fifty-six".