21621344451221 has 8 divisors (see below), whose sum is σ = 21775759428864. Its totient is φ = 21467140858800.

The previous prime is 21621344451209. The next prime is 21621344451247. The reversal of 21621344451221 is 12215444312612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21621344451221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621344451521) 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, 52641005 + ... + 53050146.

It is an arithmetic number, because the mean of its divisors is an integer number (2721969928608).

Almost surely, 2^{21621344451221} is an apocalyptic number.

It is an amenable number.

21621344451221 is a deficient number, since it is larger than the sum of its proper divisors (154414977643).

21621344451221 is a wasteful number, since it uses less digits than its factorization.

21621344451221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105692611.

The product of its digits is 92160, while the sum is 38.

Adding to 21621344451221 its reverse (12215444312612), we get a palindrome (33836788763833).

The spelling of 21621344451221 in words is "twenty-one trillion, six hundred twenty-one billion, three hundred forty-four million, four hundred fifty-one thousand, two hundred twenty-one".