21621612535021 has 2 divisors, whose sum is σ = 21621612535022. Its totient is φ = 21621612535020.

The previous prime is 21621612534911. The next prime is 21621612535087. The reversal of 21621612535021 is 12053521612612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16190564062500 + 5431048472521 = 4023750^2 + 2330461^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621612535021 - 2³⁵ = 21587252796653 is a prime.

It is a super-2 number, since 2×21621612535021² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21621612533021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810806267510 + 10810806267511.

It is an arithmetic number, because the mean of its divisors is an integer number (10810806267511).

Almost surely, 2^{21621612535021} is an apocalyptic number.

It is an amenable number.

21621612535021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621612535021 is an equidigital number, since it uses as much as digits as its factorization.

21621612535021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21621612535021 in words is "twenty-one trillion, six hundred twenty-one billion, six hundred twelve million, five hundred thirty-five thousand, twenty-one".