17918625421 has 2 divisors, whose sum is σ = 17918625422. Its totient is φ = 17918625420.

The previous prime is 17918625359. The next prime is 17918625427. The reversal of 17918625421 is 12452681971.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17367549796 + 551075625 = 131786^2 + 23475^2 .

It is a cyclic number.

It is not a de Polignac number, because 17918625421 - 2⁷ = 17918625293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17918625427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8959312710 + 8959312711.

It is an arithmetic number, because the mean of its divisors is an integer number (8959312711).

Almost surely, 2^17918625421 is an apocalyptic number.

It is an amenable number.

17918625421 is a deficient number, since it is larger than the sum of its proper divisors (1).

17918625421 is an equidigital number, since it uses as much as digits as its factorization.

17918625421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 46.

The spelling of 17918625421 in words is "seventeen billion, nine hundred eighteen million, six hundred twenty-five thousand, four hundred twenty-one".