18516409 has 2 divisors, whose sum is σ = 18516410. Its totient is φ = 18516408.

The previous prime is 18516401. The next prime is 18516437. The reversal of 18516409 is 90461581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9784384 + 8732025 = 3128^2 + 2955^2 .

It is a cyclic number.

It is not a de Polignac number, because 18516409 - 2³ = 18516401 is a prime.

It is not a weakly prime, because it can be changed into another prime (18516401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9258204 + 9258205.

It is an arithmetic number, because the mean of its divisors is an integer number (9258205).

Almost surely, 2^18516409 is an apocalyptic number.

It is an amenable number.

18516409 is a deficient number, since it is larger than the sum of its proper divisors (1).

18516409 is an equidigital number, since it uses as much as digits as its factorization.

18516409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 18516409 is about 4303.0697182360. The cubic root of 18516409 is about 264.5567956575.

The spelling of 18516409 in words is "eighteen million, five hundred sixteen thousand, four hundred nine".