21565958660 has 24 divisors (see below), whose sum is σ = 45964464000. Its totient is φ = 8497630944.

The previous prime is 21565958611. The next prime is 21565958681. The reversal of 21565958660 is 6685956512.

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, 8045660 + ... + 8048339.

It is an arithmetic number, because the mean of its divisors is an integer number (1915186000).

Almost surely, 2^21565958660 is an apocalyptic number.

21565958660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21565958660 is an abundant number, since it is smaller than the sum of its proper divisors (24398505340).

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

21565958660 is a wasteful number, since it uses less digits than its factorization.

21565958660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16094075 (or 16094073 counting only the distinct ones).

The product of its (nonzero) digits is 3888000, while the sum is 53.

The spelling of 21565958660 in words is "twenty-one billion, five hundred sixty-five million, nine hundred fifty-eight thousand, six hundred sixty".