18049891 has 2 divisors, whose sum is σ = 18049892. Its totient is φ = 18049890.

The previous prime is 18049883. The next prime is 18049901. The reversal of 18049891 is 19894081.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18049891 - 2³ = 18049883 is a prime.

It is a super-2 number, since 2×18049891² = 651597130223762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18049831) 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, 9024945 + 9024946.

It is an arithmetic number, because the mean of its divisors is an integer number (9024946).

Almost surely, 2^18049891 is an apocalyptic number.

18049891 is a deficient number, since it is larger than the sum of its proper divisors (1).

18049891 is an equidigital number, since it uses as much as digits as its factorization.

18049891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 40.

The square root of 18049891 is about 4248.5163292613. The cubic root of 18049891 is about 262.3160482957.

The spelling of 18049891 in words is "eighteen million, forty-nine thousand, eight hundred ninety-one".