18931117 has 2 divisors, whose sum is σ = 18931118. Its totient is φ = 18931116.

The previous prime is 18931103. The next prime is 18931127. The reversal of 18931117 is 71113981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17065161 + 1865956 = 4131^2 + 1366^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18931117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18931127) 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, 9465558 + 9465559.

It is an arithmetic number, because the mean of its divisors is an integer number (9465559).

Almost surely, 2^18931117 is an apocalyptic number.

It is an amenable number.

18931117 is a deficient number, since it is larger than the sum of its proper divisors (1).

18931117 is an equidigital number, since it uses as much as digits as its factorization.

18931117 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 31.

The square root of 18931117 is about 4350.9903470359. The cubic root of 18931117 is about 266.5173050726.

The spelling of 18931117 in words is "eighteen million, nine hundred thirty-one thousand, one hundred seventeen".