18713621 has 4 divisors (see below), whose sum is σ = 18808812. Its totient is φ = 18618432.

The previous prime is 18713603. The next prime is 18713633. The reversal of 18713621 is 12631781.

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 10817521 + 7896100 = 3289^2 + 2810^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18713621 is a prime.

It is a super-2 number, since 2×18713621² = 700399221863282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18713521) 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, 47300 + ... + 47693.

It is an arithmetic number, because the mean of its divisors is an integer number (4702203).

Almost surely, 2^18713621 is an apocalyptic number.

It is an amenable number.

18713621 is a deficient number, since it is larger than the sum of its proper divisors (95191).

18713621 is an equidigital number, since it uses as much as digits as its factorization.

18713621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95190.

The product of its digits is 2016, while the sum is 29.

The square root of 18713621 is about 4325.9242942983. The cubic root of 18713621 is about 265.4927156958.

The spelling of 18713621 in words is "eighteen million, seven hundred thirteen thousand, six hundred twenty-one".