21516385215 has 16 divisors (see below), whose sum is σ = 37074387168. Its totient is φ = 10592681856.

The previous prime is 21516385211. The next prime is 21516385229. The reversal of 21516385215 is 51258361512.

It is not a de Polignac number, because 21516385215 - 2² = 21516385211 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516385211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 55170024 + ... + 55170413.

It is an arithmetic number, because the mean of its divisors is an integer number (2317149198).

Almost surely, 2^21516385215 is an apocalyptic number.

21516385215 is a deficient number, since it is larger than the sum of its proper divisors (15558001953).

21516385215 is a wasteful number, since it uses less digits than its factorization.

21516385215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110340458.

The product of its digits is 72000, while the sum is 39.

The spelling of 21516385215 in words is "twenty-one billion, five hundred sixteen million, three hundred eighty-five thousand, two hundred fifteen".