18805621 has 4 divisors (see below), whose sum is σ = 19911852. Its totient is φ = 17699392.

The previous prime is 18805613. The next prime is 18805643. The reversal of 18805621 is 12650881.

18805621 is nontrivially palindromic in base 13.

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

It can be written as a sum of positive squares in 2 ways, for example, as 16200625 + 2604996 = 4025^2 + 1614^2 .

It is a cyclic number.

It is not a de Polignac number, because 18805621 - 2³ = 18805613 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 (18805321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 553090 + ... + 553123.

It is an arithmetic number, because the mean of its divisors is an integer number (4977963).

Almost surely, 2^18805621 is an apocalyptic number.

It is an amenable number.

18805621 is a deficient number, since it is larger than the sum of its proper divisors (1106231).

18805621 is a wasteful number, since it uses less digits than its factorization.

18805621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106230.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 18805621 is about 4336.5448227823. The cubic root of 18805621 is about 265.9270768877.

The spelling of 18805621 in words is "eighteen million, eight hundred five thousand, six hundred twenty-one".