20997787928 has 32 divisors (see below), whose sum is σ = 42496053600. Its totient is φ = 9669189888.

The previous prime is 20997787841. The next prime is 20997787931. The reversal of 20997787928 is 82978779902.

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, 184301 + ... + 275612.

It is an arithmetic number, because the mean of its divisors is an integer number (1328001675).

Almost surely, 2^20997787928 is an apocalyptic number.

It is an amenable number.

20997787928 is an abundant number, since it is smaller than the sum of its proper divisors (21498265672).

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

20997787928 is a wasteful number, since it uses less digits than its factorization.

20997787928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460371 (or 460367 counting only the distinct ones).

The product of its (nonzero) digits is 64012032, while the sum is 68.

The spelling of 20997787928 in words is "twenty billion, nine hundred ninety-seven million, seven hundred eighty-seven thousand, nine hundred twenty-eight".