18657601621 has 2 divisors, whose sum is σ = 18657601622. Its totient is φ = 18657601620.

The previous prime is 18657601579. The next prime is 18657601631. The reversal of 18657601621 is 12610675681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18580688721 + 76912900 = 136311^2 + 8770^2 .

It is a cyclic number.

It is not a de Polignac number, because 18657601621 - 2²⁹ = 18120730709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18657601631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9328800810 + 9328800811.

It is an arithmetic number, because the mean of its divisors is an integer number (9328800811).

Almost surely, 2^18657601621 is an apocalyptic number.

It is an amenable number.

18657601621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18657601621 is an equidigital number, since it uses as much as digits as its factorization.

18657601621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 43.

The spelling of 18657601621 in words is "eighteen billion, six hundred fifty-seven million, six hundred one thousand, six hundred twenty-one".