18305621 has 4 divisors (see below), whose sum is σ = 18327372. Its totient is φ = 18283872.

The previous prime is 18305611. The next prime is 18305627. The reversal of 18305621 is 12650381.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12650381 = 673 ⋅18797.

It can be written as a sum of positive squares in 2 ways, for example, as 10956100 + 7349521 = 3310^2 + 2711^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18305621 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 (18305627) 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, 9560 + ... + 11313.

It is an arithmetic number, because the mean of its divisors is an integer number (4581843).

Almost surely, 2^18305621 is an apocalyptic number.

It is an amenable number.

18305621 is a deficient number, since it is larger than the sum of its proper divisors (21751).

18305621 is an equidigital number, since it uses as much as digits as its factorization.

18305621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21750.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 18305621 is about 4278.5068657185. The cubic root of 18305621 is about 263.5490704796.

The spelling of 18305621 in words is "eighteen million, three hundred five thousand, six hundred twenty-one".