18931589 has 2 divisors, whose sum is σ = 18931590. Its totient is φ = 18931588.

The previous prime is 18931579. The next prime is 18931603. The reversal of 18931589 is 98513981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18130564 + 801025 = 4258^2 + 895^2 .

It is an emirp because it is prime and its reverse (98513981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18931589 - 2²⁰ = 17883013 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18931559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9465794 + 9465795.

It is an arithmetic number, because the mean of its divisors is an integer number (9465795).

Almost surely, 2^18931589 is an apocalyptic number.

It is an amenable number.

18931589 is a deficient number, since it is larger than the sum of its proper divisors (1).

18931589 is an equidigital number, since it uses as much as digits as its factorization.

18931589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 77760, while the sum is 44.

The square root of 18931589 is about 4351.0445872227. The cubic root of 18931589 is about 266.5195200347.

The spelling of 18931589 in words is "eighteen million, nine hundred thirty-one thousand, five hundred eighty-nine".