18913021 has 2 divisors, whose sum is σ = 18913022. Its totient is φ = 18913020.

The previous prime is 18913003. The next prime is 18913039. The reversal of 18913021 is 12031981.

It is a balanced prime because it is at equal distance from previous prime (18913003) and next prime (18913039).

It can be written as a sum of positive squares in only one way, i.e., 18156121 + 756900 = 4261^2 + 870^2 .

It is a cyclic number.

It is not a de Polignac number, because 18913021 - 2⁷ = 18912893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18913001) 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, 9456510 + 9456511.

It is an arithmetic number, because the mean of its divisors is an integer number (9456511).

Almost surely, 2^18913021 is an apocalyptic number.

It is an amenable number.

18913021 is a deficient number, since it is larger than the sum of its proper divisors (1).

18913021 is an equidigital number, since it uses as much as digits as its factorization.

18913021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 18913021 is about 4348.9103232879. The cubic root of 18913021 is about 266.4323578983.

The spelling of 18913021 in words is "eighteen million, nine hundred thirteen thousand, twenty-one".