21286920928 has 72 divisors (see below), whose sum is σ = 51863344848. Its totient is φ = 8421184512.

The previous prime is 21286920869. The next prime is 21286920931. The reversal of 21286920928 is 82902968212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 243301 + ... + 319012.

It is an arithmetic number, because the mean of its divisors is an integer number (720324234).

Almost surely, 2^21286920928 is an apocalyptic number.

21286920928 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21286920928 is an abundant number, since it is smaller than the sum of its proper divisors (30576423920).

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

21286920928 is a wasteful number, since it uses less digits than its factorization.

21286920928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562356 (or 562335 counting only the distinct ones).

The product of its (nonzero) digits is 497664, while the sum is 49.

The spelling of 21286920928 in words is "twenty-one billion, two hundred eighty-six million, nine hundred twenty thousand, nine hundred twenty-eight".