18621399 has 4 divisors (see below), whose sum is σ = 24828536. Its totient is φ = 12414264.

The previous prime is 18621373. The next prime is 18621431. The reversal of 18621399 is 99312681.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 18621399 - 2⁵ = 18621367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18621319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3103564 + ... + 3103569.

It is an arithmetic number, because the mean of its divisors is an integer number (6207134).

Almost surely, 2^18621399 is an apocalyptic number.

18621399 is a deficient number, since it is larger than the sum of its proper divisors (6207137).

18621399 is an equidigital number, since it uses as much as digits as its factorization.

18621399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6207136.

The product of its digits is 23328, while the sum is 39.

The square root of 18621399 is about 4315.2519045822. The cubic root of 18621399 is about 265.0558752477.

The spelling of 18621399 in words is "eighteen million, six hundred twenty-one thousand, three hundred ninety-nine".