18424621 has 4 divisors (see below), whose sum is σ = 18874044. Its totient is φ = 17975200.

The previous prime is 18424613. The next prime is 18424639. The reversal of 18424621 is 12642481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12642481 = 191 ⋅66191.

It can be written as a sum of positive squares in 2 ways, for example, as 1729225 + 16695396 = 1315^2 + 4086^2 .

It is a cyclic number.

It is not a de Polignac number, because 18424621 - 2³ = 18424613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18424621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18424121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224650 + ... + 224731.

It is an arithmetic number, because the mean of its divisors is an integer number (4718511).

Almost surely, 2^18424621 is an apocalyptic number.

It is an amenable number.

18424621 is a deficient number, since it is larger than the sum of its proper divisors (449423).

18424621 is an equidigital number, since it uses as much as digits as its factorization.

18424621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449422.

The product of its digits is 3072, while the sum is 28.

The square root of 18424621 is about 4292.3910586059. The cubic root of 18424621 is about 264.1189250312.

The spelling of 18424621 in words is "eighteen million, four hundred twenty-four thousand, six hundred twenty-one".