21591949368 has 32 divisors (see below), whose sum is σ = 58887135360. Its totient is φ = 6543014880.

The previous prime is 21591949349. The next prime is 21591949369. The reversal of 21591949368 is 86394919512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21591949369) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40893580 + ... + 40894107.

It is an arithmetic number, because the mean of its divisors is an integer number (1840222980).

Almost surely, 2^21591949368 is an apocalyptic number.

It is an amenable number.

21591949368 is an abundant number, since it is smaller than the sum of its proper divisors (37295185992).

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

21591949368 is a wasteful number, since it uses less digits than its factorization.

21591949368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81787707 (or 81787703 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 57.

The spelling of 21591949368 in words is "twenty-one billion, five hundred ninety-one million, nine hundred forty-nine thousand, three hundred sixty-eight".