21240521056 has 24 divisors (see below), whose sum is σ = 42118128360. Its totient is φ = 10543853568.

The previous prime is 21240521041. The next prime is 21240521077. The reversal of 21240521056 is 65012504212.

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, 2383201 + ... + 2392096.

It is an arithmetic number, because the mean of its divisors is an integer number (1754922015).

Almost surely, 2^21240521056 is an apocalyptic number.

It is an amenable number.

21240521056 is a deficient number, since it is larger than the sum of its proper divisors (20877607304).

21240521056 is a wasteful number, since it uses less digits than its factorization.

21240521056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4775446 (or 4775438 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The spelling of 21240521056 in words is "twenty-one billion, two hundred forty million, five hundred twenty-one thousand, fifty-six".