18198391 has 2 divisors, whose sum is σ = 18198392. Its totient is φ = 18198390.

The previous prime is 18198379. The next prime is 18198407. The reversal of 18198391 is 19389181.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18198391 - 2⁷ = 18198263 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18198091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9099195 + 9099196.

It is an arithmetic number, because the mean of its divisors is an integer number (9099196).

Almost surely, 2^18198391 is an apocalyptic number.

18198391 is a deficient number, since it is larger than the sum of its proper divisors (1).

18198391 is an equidigital number, since it uses as much as digits as its factorization.

18198391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 40.

The square root of 18198391 is about 4265.9572196636. The cubic root of 18198391 is about 263.0334596743.

The spelling of 18198391 in words is "eighteen million, one hundred ninety-eight thousand, three hundred ninety-one".