18623621 has 4 divisors (see below), whose sum is σ = 18632544. Its totient is φ = 18614700.

The previous prime is 18623611. The next prime is 18623639. The reversal of 18623621 is 12632681.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12632681 = 23 ⋅549247.

It is a cyclic number.

It is not a de Polignac number, because 18623621 - 2⁶ = 18623557 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 (18623611) 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, 536 + ... + 6126.

It is an arithmetic number, because the mean of its divisors is an integer number (4658136).

Almost surely, 2^18623621 is an apocalyptic number.

It is an amenable number.

18623621 is a deficient number, since it is larger than the sum of its proper divisors (8923).

18623621 is an equidigital number, since it uses as much as digits as its factorization.

18623621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8922.

The product of its digits is 3456, while the sum is 29.

The square root of 18623621 is about 4315.5093558003. The cubic root of 18623621 is about 265.0664174332.

The spelling of 18623621 in words is "eighteen million, six hundred twenty-three thousand, six hundred twenty-one".