18212890621 has 2 divisors, whose sum is σ = 18212890622. Its totient is φ = 18212890620.

The previous prime is 18212890609. The next prime is 18212890627. The reversal of 18212890621 is 12609821281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18100742521 + 112148100 = 134539^2 + 10590^2 .

It is a cyclic number.

It is not a de Polignac number, because 18212890621 - 2⁵ = 18212890589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18212890627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9106445310 + 9106445311.

It is an arithmetic number, because the mean of its divisors is an integer number (9106445311).

Almost surely, 2^18212890621 is an apocalyptic number.

It is an amenable number.

18212890621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18212890621 is an equidigital number, since it uses as much as digits as its factorization.

18212890621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27648, while the sum is 40.

The spelling of 18212890621 in words is "eighteen billion, two hundred twelve million, eight hundred ninety thousand, six hundred twenty-one".