18891137 has 2 divisors, whose sum is σ = 18891138. Its totient is φ = 18891136.

The previous prime is 18891113. The next prime is 18891143. The reversal of 18891137 is 73119881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18395521 + 495616 = 4289^2 + 704^2 .

It is a cyclic number.

It is not a de Polignac number, because 18891137 - 2⁸ = 18890881 is a prime.

It is a Chen prime.

It is a nialpdrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 18891137.

It is not a weakly prime, because it can be changed into another prime (18891637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445568 + 9445569.

It is an arithmetic number, because the mean of its divisors is an integer number (9445569).

Almost surely, 2^18891137 is an apocalyptic number.

It is an amenable number.

18891137 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891137 is an equidigital number, since it uses as much as digits as its factorization.

18891137 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 38.

The square root of 18891137 is about 4346.3935624837. The cubic root of 18891137 is about 266.3295564826.

The spelling of 18891137 in words is "eighteen million, eight hundred ninety-one thousand, one hundred thirty-seven".