21398712621 has 16 divisors (see below), whose sum is σ = 33519662400. Its totient is φ = 11971307520.

The previous prime is 21398712613. The next prime is 21398712631. The reversal of 21398712621 is 12621789312.

It is not a de Polignac number, because 21398712621 - 2³ = 21398712613 is a prime.

It is a super-2 number, since 2×21398712621² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21398712611) 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, 24939796 + ... + 24940653.

It is an arithmetic number, because the mean of its divisors is an integer number (2094978900).

Almost surely, 2^21398712621 is an apocalyptic number.

It is an amenable number.

21398712621 is a deficient number, since it is larger than the sum of its proper divisors (12120949779).

21398712621 is a wasteful number, since it uses less digits than its factorization.

21398712621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49880476.

The product of its digits is 72576, while the sum is 42.

The spelling of 21398712621 in words is "twenty-one billion, three hundred ninety-eight million, seven hundred twelve thousand, six hundred twenty-one".