21656120616015 has 16 divisors (see below), whose sum is σ = 35387022624768. Its totient is φ = 11304187782176.

The previous prime is 21656120616007. The next prime is 21656120616101. The reversal of 21656120616015 is 51061602165612.

It is a cyclic number.

It is not a de Polignac number, because 21656120616015 - 2³ = 21656120616007 is a prime.

It is a congruent number.

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, 15358950087 + ... + 15358951496.

It is an arithmetic number, because the mean of its divisors is an integer number (2211688914048).

Almost surely, 2^{21656120616015} is an apocalyptic number.

21656120616015 is a deficient number, since it is larger than the sum of its proper divisors (13730902008753).

21656120616015 is a wasteful number, since it uses less digits than its factorization.

21656120616015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30717901638.

The product of its (nonzero) digits is 129600, while the sum is 42.

The spelling of 21656120616015 in words is "twenty-one trillion, six hundred fifty-six billion, one hundred twenty million, six hundred sixteen thousand, fifteen".