21079615665 has 16 divisors (see below), whose sum is σ = 33913728576. Its totient is φ = 11180347200.

The previous prime is 21079615619. The next prime is 21079615679. The reversal of 21079615665 is 56651697012.

It is not a de Polignac number, because 21079615665 - 2⁹ = 21079615153 is a prime.

It is a super-2 number, since 2×21079615665² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3879351 + ... + 3884780.

It is an arithmetic number, because the mean of its divisors is an integer number (2119608036).

Almost surely, 2^21079615665 is an apocalyptic number.

It is an amenable number.

21079615665 is a deficient number, since it is larger than the sum of its proper divisors (12834112911).

21079615665 is a wasteful number, since it uses less digits than its factorization.

21079615665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7764320.

The product of its (nonzero) digits is 680400, while the sum is 48.

The spelling of 21079615665 in words is "twenty-one billion, seventy-nine million, six hundred fifteen thousand, six hundred sixty-five".