18904987 has 2 divisors, whose sum is σ = 18904988. Its totient is φ = 18904986.

The previous prime is 18904939. The next prime is 18904997. The reversal of 18904987 is 78940981.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18904987 - 2⁷ = 18904859 is a prime.

It is not a weakly prime, because it can be changed into another prime (18904927) 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, 9452493 + 9452494.

It is an arithmetic number, because the mean of its divisors is an integer number (9452494).

Almost surely, 2^18904987 is an apocalyptic number.

18904987 is a deficient number, since it is larger than the sum of its proper divisors (1).

18904987 is an equidigital number, since it uses as much as digits as its factorization.

18904987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 18904987 is about 4347.9865455174. The cubic root of 18904987 is about 266.3946269135.

It can be divided in two parts, 18904 and 987, that added together give a palindrome (19891).

The spelling of 18904987 in words is "eighteen million, nine hundred four thousand, nine hundred eighty-seven".