18139897 has 2 divisors, whose sum is σ = 18139898. Its totient is φ = 18139896.

The previous prime is 18139883. The next prime is 18139907. The reversal of 18139897 is 79893181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17147881 + 992016 = 4141^2 + 996^2 .

It is an emirp because it is prime and its reverse (79893181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18139897 - 2⁷ = 18139769 is a prime.

It is not a weakly prime, because it can be changed into another prime (18136897) 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, 9069948 + 9069949.

It is an arithmetic number, because the mean of its divisors is an integer number (9069949).

Almost surely, 2^18139897 is an apocalyptic number.

It is an amenable number.

18139897 is a deficient number, since it is larger than the sum of its proper divisors (1).

18139897 is an equidigital number, since it uses as much as digits as its factorization.

18139897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 46.

The square root of 18139897 is about 4259.0957960581. The cubic root of 18139897 is about 262.7513396172.

The spelling of 18139897 in words is "eighteen million, one hundred thirty-nine thousand, eight hundred ninety-seven".