18509621 has 16 divisors (see below), whose sum is σ = 20563200. Its totient is φ = 16555968.

The previous prime is 18509599. The next prime is 18509633. The reversal of 18509621 is 12690581.

It is not a de Polignac number, because 18509621 - 2²² = 14315317 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18509671) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 68675 + ... + 68943.

It is an arithmetic number, because the mean of its divisors is an integer number (1285200).

Almost surely, 2^18509621 is an apocalyptic number.

It is an amenable number.

18509621 is a deficient number, since it is larger than the sum of its proper divisors (2053579).

18509621 is a wasteful number, since it uses less digits than its factorization.

18509621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 18509621 is about 4302.2809066819. The cubic root of 18509621 is about 264.5244634161.

The spelling of 18509621 in words is "eighteen million, five hundred nine thousand, six hundred twenty-one".