18998491 has 2 divisors, whose sum is σ = 18998492. Its totient is φ = 18998490.

The previous prime is 18998477. The next prime is 18998519. The reversal of 18998491 is 19489981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18998491 - 2⁷ = 18998363 is a prime.

It is not a weakly prime, because it can be changed into another prime (18998411) 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, 9499245 + 9499246.

It is an arithmetic number, because the mean of its divisors is an integer number (9499246).

Almost surely, 2^18998491 is an apocalyptic number.

18998491 is a deficient number, since it is larger than the sum of its proper divisors (1).

18998491 is an equidigital number, since it uses as much as digits as its factorization.

18998491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 186624, while the sum is 49.

The square root of 18998491 is about 4358.7258459325. The cubic root of 18998491 is about 266.8331004429.

The spelling of 18998491 in words is "eighteen million, nine hundred ninety-eight thousand, four hundred ninety-one".