18310021 has 2 divisors, whose sum is σ = 18310022. Its totient is φ = 18310020.

The previous prime is 18310013. The next prime is 18310043. The reversal of 18310021 is 12001381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14737921 + 3572100 = 3839^2 + 1890^2 .

It is a cyclic number.

It is not a de Polignac number, because 18310021 - 2³ = 18310013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18309977 and 18310004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18310121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9155010 + 9155011.

It is an arithmetic number, because the mean of its divisors is an integer number (9155011).

Almost surely, 2^18310021 is an apocalyptic number.

It is an amenable number.

18310021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18310021 is an equidigital number, since it uses as much as digits as its factorization.

18310021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 18310021 is about 4279.0210328999. The cubic root of 18310021 is about 263.5701846320.

The spelling of 18310021 in words is "eighteen million, three hundred ten thousand, twenty-one".