21515560427521 has 8 divisors (see below), whose sum is σ = 21528270720000. Its totient is φ = 21502852446240.

The previous prime is 21515560427507. The next prime is 21515560427531. The reversal of 21515560427521 is 12572406551512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21515560427521 - 2¹⁵ = 21515560394753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21515560427531) 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, 18226656 + ... + 19371166.

It is an arithmetic number, because the mean of its divisors is an integer number (2691033840000).

Almost surely, 2^{21515560427521} is an apocalyptic number.

It is an amenable number.

21515560427521 is a deficient number, since it is larger than the sum of its proper divisors (12710292479).

21515560427521 is a wasteful number, since it uses less digits than its factorization.

21515560427521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155599.

The product of its (nonzero) digits is 840000, while the sum is 46.

The spelling of 21515560427521 in words is "twenty-one trillion, five hundred fifteen billion, five hundred sixty million, four hundred twenty-seven thousand, five hundred twenty-one".