21997931790 has 16 divisors (see below), whose sum is σ = 52795036368. Its totient is φ = 5866115136.

The previous prime is 21997931743. The next prime is 21997931803. The reversal of 21997931790 is 9713979912.

It is a self number, because there is not a number n which added to its sum of digits gives 21997931790.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 366632167 + ... + 366632226.

It is an arithmetic number, because the mean of its divisors is an integer number (3299689773).

Almost surely, 2^21997931790 is an apocalyptic number.

21997931790 is an abundant number, since it is smaller than the sum of its proper divisors (30797104578).

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

21997931790 is a wasteful number, since it uses less digits than its factorization.

21997931790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733264403.

The product of its (nonzero) digits is 1928934, while the sum is 57.

The spelling of 21997931790 in words is "twenty-one billion, nine hundred ninety-seven million, nine hundred thirty-one thousand, seven hundred ninety".