21221331056 has 20 divisors (see below), whose sum is σ = 42227582232. Its totient is φ = 10323890496.

The previous prime is 21221331029. The next prime is 21221331071. The reversal of 21221331056 is 65013312212.

It is a happy number.

It is a congruent number.

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, 17922830 + ... + 17924013.

Almost surely, 2^21221331056 is an apocalyptic number.

It is an amenable number.

21221331056 is a deficient number, since it is larger than the sum of its proper divisors (21006251176).

21221331056 is a wasteful number, since it uses less digits than its factorization.

21221331056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35846888 (or 35846882 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

Adding to 21221331056 its reverse (65013312212), we get a palindrome (86234643268).

The spelling of 21221331056 in words is "twenty-one billion, two hundred twenty-one million, three hundred thirty-one thousand, fifty-six".