18517004106221 has 2 divisors, whose sum is σ = 18517004106222. Its totient is φ = 18517004106220.

The previous prime is 18517004106179. The next prime is 18517004106247. The reversal of 18517004106221 is 12260140071581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12159092286121 + 6357911820100 = 3486989^2 + 2521490^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18517004106221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18517004106121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9258502053110 + 9258502053111.

It is an arithmetic number, because the mean of its divisors is an integer number (9258502053111).

Almost surely, 2^{18517004106221} is an apocalyptic number.

It is an amenable number.

18517004106221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18517004106221 is an equidigital number, since it uses as much as digits as its factorization.

18517004106221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 26880, while the sum is 38.

The spelling of 18517004106221 in words is "eighteen trillion, five hundred seventeen billion, four million, one hundred six thousand, two hundred twenty-one".