18330991 has 8 divisors (see below), whose sum is σ = 22052480. Its totient is φ = 14885208.

The previous prime is 18330979. The next prime is 18331003. The reversal of 18330991 is 19903381.

It is an interprime number because it is at equal distance from previous prime (18330979) and next prime (18331003).

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

It is not a de Polignac number, because 18330991 - 2⁹ = 18330479 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 (18330901) 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, 68781 + ... + 69046.

It is an arithmetic number, because the mean of its divisors is an integer number (2756560).

Almost surely, 2^18330991 is an apocalyptic number.

18330991 is a deficient number, since it is larger than the sum of its proper divisors (3721489).

18330991 is a wasteful number, since it uses less digits than its factorization.

18330991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137853.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 18330991 is about 4281.4706585471. The cubic root of 18330991 is about 263.6707663137.

It can be divided in two parts, 18330 and 991, that added together give a square (19321 = 139²).

The spelling of 18330991 in words is "eighteen million, three hundred thirty thousand, nine hundred ninety-one".