18240391 has 8 divisors (see below), whose sum is σ = 20321280. Its totient is φ = 16256352.

The previous prime is 18240377. The next prime is 18240401. The reversal of 18240391 is 19304281.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18240391 - 2⁵ = 18240359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18240301) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23815 + ... + 24568.

It is an arithmetic number, because the mean of its divisors is an integer number (2540160).

Almost surely, 2^18240391 is an apocalyptic number.

18240391 is a deficient number, since it is larger than the sum of its proper divisors (2080889).

18240391 is a wasteful number, since it uses less digits than its factorization.

18240391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48425.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 18240391 is about 4270.8770761988. The cubic root of 18240391 is about 263.2356555247.

The spelling of 18240391 in words is "eighteen million, two hundred forty thousand, three hundred ninety-one".