18331609 has 2 divisors, whose sum is σ = 18331610. Its totient is φ = 18331608.

The previous prime is 18331589. The next prime is 18331639. The reversal of 18331609 is 90613381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17875984 + 455625 = 4228^2 + 675^2 .

It is an emirp because it is prime and its reverse (90613381) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18331609 is a prime.

It is not a weakly prime, because it can be changed into another prime (18331639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9165804 + 9165805.

It is an arithmetic number, because the mean of its divisors is an integer number (9165805).

Almost surely, 2^18331609 is an apocalyptic number.

It is an amenable number.

18331609 is a deficient number, since it is larger than the sum of its proper divisors (1).

18331609 is an equidigital number, since it uses as much as digits as its factorization.

18331609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 18331609 is about 4281.5428294016. The cubic root of 18331609 is about 263.6737293595.

The spelling of 18331609 in words is "eighteen million, three hundred thirty-one thousand, six hundred nine".