21206102422621 has 2 divisors, whose sum is σ = 21206102422622. Its totient is φ = 21206102422620.

The previous prime is 21206102422607. The next prime is 21206102422679. The reversal of 21206102422621 is 12622420160212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19831088210521 + 1375014212100 = 4453211^2 + 1172610^2 .

It is a cyclic number.

It is not a de Polignac number, because 21206102422621 - 2⁷ = 21206102422493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21206102422121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10603051211310 + 10603051211311.

It is an arithmetic number, because the mean of its divisors is an integer number (10603051211311).

Almost surely, 2^{21206102422621} is an apocalyptic number.

It is an amenable number.

21206102422621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21206102422621 is an equidigital number, since it uses as much as digits as its factorization.

21206102422621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 31.

Adding to 21206102422621 its reverse (12622420160212), we get a palindrome (33828522582833).

The spelling of 21206102422621 in words is "twenty-one trillion, two hundred six billion, one hundred two million, four hundred twenty-two thousand, six hundred twenty-one".