18918157 has 2 divisors, whose sum is σ = 18918158. Its totient is φ = 18918156.

The previous prime is 18918143. The next prime is 18918181. The reversal of 18918157 is 75181981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18913801 + 4356 = 4349^2 + 66^2 .

It is a cyclic number.

It is not a de Polignac number, because 18918157 - 2¹¹ = 18916109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18918457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9459078 + 9459079.

It is an arithmetic number, because the mean of its divisors is an integer number (9459079).

Almost surely, 2^18918157 is an apocalyptic number.

It is an amenable number.

18918157 is a deficient number, since it is larger than the sum of its proper divisors (1).

18918157 is an equidigital number, since it uses as much as digits as its factorization.

18918157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 40.

The square root of 18918157 is about 4349.5007759512. The cubic root of 18918157 is about 266.4564730788.

The spelling of 18918157 in words is "eighteen million, nine hundred eighteen thousand, one hundred fifty-seven".