21515512271221 has 16 divisors (see below), whose sum is σ = 22802173128000. Its totient is φ = 20265251529600.

The previous prime is 21515512271191. The next prime is 21515512271269. The reversal of 21515512271221 is 12217221551512.

It is a cyclic number.

It is not a de Polignac number, because 21515512271221 - 2⁵ = 21515512271189 is a prime.

It is a super-2 number, since 2×21515512271221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21515512271021) 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, 13777930 + ... + 15259828.

It is an arithmetic number, because the mean of its divisors is an integer number (1425135820500).

Almost surely, 2^{21515512271221} is an apocalyptic number.

It is an amenable number.

21515512271221 is a deficient number, since it is larger than the sum of its proper divisors (1286660856779).

21515512271221 is a wasteful number, since it uses less digits than its factorization.

21515512271221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1494180.

The product of its digits is 28000, while the sum is 37.

The spelling of 21515512271221 in words is "twenty-one trillion, five hundred fifteen billion, five hundred twelve million, two hundred seventy-one thousand, two hundred twenty-one".