18449891 has 2 divisors, whose sum is σ = 18449892. Its totient is φ = 18449890.

The previous prime is 18449861. The next prime is 18449911. The reversal of 18449891 is 19894481.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18449891 - 2²² = 14255587 is a prime.

It is not a weakly prime, because it can be changed into another prime (18449861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9224945 + 9224946.

It is an arithmetic number, because the mean of its divisors is an integer number (9224946).

Almost surely, 2^18449891 is an apocalyptic number.

18449891 is a deficient number, since it is larger than the sum of its proper divisors (1).

18449891 is an equidigital number, since it uses as much as digits as its factorization.

18449891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82944, while the sum is 44.

The square root of 18449891 is about 4295.3336308138. Note that the first 3 decimals coincide. The cubic root of 18449891 is about 264.2396192592.

The spelling of 18449891 in words is "eighteen million, four hundred forty-nine thousand, eight hundred ninety-one".