18506021 has 2 divisors, whose sum is σ = 18506022. Its totient is φ = 18506020.

The previous prime is 18505969. The next prime is 18506027. The reversal of 18506021 is 12060581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17757796 + 748225 = 4214^2 + 865^2 .

It is a cyclic number.

It is not a de Polignac number, because 18506021 - 2¹⁴ = 18489637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18506027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9253010 + 9253011.

It is an arithmetic number, because the mean of its divisors is an integer number (9253011).

Almost surely, 2^18506021 is an apocalyptic number.

It is an amenable number.

18506021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18506021 is an equidigital number, since it uses as much as digits as its factorization.

18506021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 18506021 is about 4301.8625036140. The cubic root of 18506021 is about 264.5073128792.

The spelling of 18506021 in words is "eighteen million, five hundred six thousand, twenty-one".