18707621 has 2 divisors, whose sum is σ = 18707622. Its totient is φ = 18707620.

The previous prime is 18707597. The next prime is 18707627. The reversal of 18707621 is 12670781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18232900 + 474721 = 4270^2 + 689^2 .

It is a cyclic number.

It is not a de Polignac number, because 18707621 - 2¹⁸ = 18445477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18707627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9353810 + 9353811.

It is an arithmetic number, because the mean of its divisors is an integer number (9353811).

Almost surely, 2^18707621 is an apocalyptic number.

It is an amenable number.

18707621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18707621 is an equidigital number, since it uses as much as digits as its factorization.

18707621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4704, while the sum is 32.

The square root of 18707621 is about 4325.2307452898. The cubic root of 18707621 is about 265.4643383877.

The spelling of 18707621 in words is "eighteen million, seven hundred seven thousand, six hundred twenty-one".