18438817 has 2 divisors, whose sum is σ = 18438818. Its totient is φ = 18438816.

The previous prime is 18438803. The next prime is 18438821. The reversal of 18438817 is 71883481.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14561856 + 3876961 = 3816^2 + 1969^2 .

It is a cyclic number.

It is not a de Polignac number, because 18438817 - 2⁷ = 18438689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18438817.

It is not a weakly prime, because it can be changed into another prime (18438877) 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, 9219408 + 9219409.

It is an arithmetic number, because the mean of its divisors is an integer number (9219409).

Almost surely, 2^18438817 is an apocalyptic number.

It is an amenable number.

18438817 is a deficient number, since it is larger than the sum of its proper divisors (1).

18438817 is an equidigital number, since it uses as much as digits as its factorization.

18438817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43008, while the sum is 40.

The square root of 18438817 is about 4294.0443640000. The cubic root of 18438817 is about 264.1867413462.

The spelling of 18438817 in words is "eighteen million, four hundred thirty-eight thousand, eight hundred seventeen".