21211864621 has 4 divisors (see below), whose sum is σ = 21212770912. Its totient is φ = 21210958332.

The previous prime is 21211864577. The next prime is 21211864637. The reversal of 21211864621 is 12646811212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21211864621 - 2⁹ = 21211864109 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 (21211861621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 417081 + ... + 465166.

It is an arithmetic number, because the mean of its divisors is an integer number (5303192728).

Almost surely, 2^21211864621 is an apocalyptic number.

It is an amenable number.

21211864621 is a deficient number, since it is larger than the sum of its proper divisors (906291).

21211864621 is an equidigital number, since it uses as much as digits as its factorization.

21211864621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906290.

The product of its digits is 9216, while the sum is 34.

The spelling of 21211864621 in words is "twenty-one billion, two hundred eleven million, eight hundred sixty-four thousand, six hundred twenty-one".