18939621 has 8 divisors (see below), whose sum is σ = 25503264. Its totient is φ = 12501200.

The previous prime is 18939617. The next prime is 18939629. The reversal of 18939621 is 12693981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18939621 - 2² = 18939617 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18939621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18939629) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30951 + ... + 31556.

It is an arithmetic number, because the mean of its divisors is an integer number (3187908).

Almost surely, 2^18939621 is an apocalyptic number.

It is an amenable number.

18939621 is a deficient number, since it is larger than the sum of its proper divisors (6563643).

18939621 is a wasteful number, since it uses less digits than its factorization.

18939621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62611.

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

The square root of 18939621 is about 4351.9674860918. The cubic root of 18939621 is about 266.5572062905.

The spelling of 18939621 in words is "eighteen million, nine hundred thirty-nine thousand, six hundred twenty-one".