18809621 has 2 divisors, whose sum is σ = 18809622. Its totient is φ = 18809620.

The previous prime is 18809597. The next prime is 18809627. The reversal of 18809621 is 12690881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13468900 + 5340721 = 3670^2 + 2311^2 .

It is a cyclic number.

It is not a de Polignac number, because 18809621 - 2¹⁴ = 18793237 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18809627) 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 as a sum of consecutive naturals, namely, 9404810 + 9404811.

It is an arithmetic number, because the mean of its divisors is an integer number (9404811).

Almost surely, 2^18809621 is an apocalyptic number.

It is an amenable number.

18809621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18809621 is an equidigital number, since it uses as much as digits as its factorization.

18809621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 18809621 is about 4337.0059949232. The cubic root of 18809621 is about 265.9459299902.

The spelling of 18809621 in words is "eighteen million, eight hundred nine thousand, six hundred twenty-one".