21621542500221 has 16 divisors (see below), whose sum is σ = 30082525863936. Its totient is φ = 13787476225776.

The previous prime is 21621542500177. The next prime is 21621542500297. The reversal of 21621542500221 is 12200524512612.

It is not a de Polignac number, because 21621542500221 - 2²⁹ = 21621005629309 is a prime.

It is a super-2 number, since 2×21621542500221² (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 (21621542000221) 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, 3641976 + ... + 7517118.

It is an arithmetic number, because the mean of its divisors is an integer number (1880157866496).

Almost surely, 2^{21621542500221} is an apocalyptic number.

It is an amenable number.

21621542500221 is a deficient number, since it is larger than the sum of its proper divisors (8460983363715).

21621542500221 is a wasteful number, since it uses less digits than its factorization.

21621542500221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3956032.

The product of its (nonzero) digits is 19200, while the sum is 33.

The spelling of 21621542500221 in words is "twenty-one trillion, six hundred twenty-one billion, five hundred forty-two million, five hundred thousand, two hundred twenty-one".