18017621 has 2 divisors, whose sum is σ = 18017622. Its totient is φ = 18017620.

The previous prime is 18017543. The next prime is 18017627. The reversal of 18017621 is 12671081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13586596 + 4431025 = 3686^2 + 2105^2 .

It is a cyclic number.

It is not a de Polignac number, because 18017621 - 2¹⁴ = 18001237 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 (18017627) 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, 9008810 + 9008811.

It is an arithmetic number, because the mean of its divisors is an integer number (9008811).

Almost surely, 2^18017621 is an apocalyptic number.

It is an amenable number.

18017621 is a deficient number, since it is larger than the sum of its proper divisors (1).

18017621 is an equidigital number, since it uses as much as digits as its factorization.

18017621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 18017621 is about 4244.7168339007. The cubic root of 18017621 is about 262.1596302043.

The spelling of 18017621 in words is "eighteen million, seventeen thousand, six hundred twenty-one".