18090391 has 8 divisors (see below), whose sum is σ = 20371968. Its totient is φ = 15915000.

The previous prime is 18090379. The next prime is 18090409. The reversal of 18090391 is 19309081.

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 18090391 - 2⁷ = 18090263 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18090301) 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, 26185 + ... + 26866.

It is an arithmetic number, because the mean of its divisors is an integer number (2546496).

Almost surely, 2^18090391 is an apocalyptic number.

18090391 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

18090391 is a deficient number, since it is larger than the sum of its proper divisors (2281577).

18090391 is a wasteful number, since it uses less digits than its factorization.

18090391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53093.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 18090391 is about 4253.2800284016. The cubic root of 18090391 is about 262.5120949831.

It can be divided in two parts, 18090 and 391, that added together give a palindrome (18481).

The spelling of 18090391 in words is "eighteen million, ninety thousand, three hundred ninety-one".