18240991 has 8 divisors (see below), whose sum is σ = 18505760. Its totient is φ = 17978112.

The previous prime is 18240979. The next prime is 18240997. The reversal of 18240991 is 19904281.

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 18240991 - 2⁹ = 18240479 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 (18240997) 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, 41911 + ... + 42343.

It is an arithmetic number, because the mean of its divisors is an integer number (2313220).

Almost surely, 2^18240991 is an apocalyptic number.

18240991 is a deficient number, since it is larger than the sum of its proper divisors (264769).

18240991 is a wasteful number, since it uses less digits than its factorization.

18240991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 945.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 18240991 is about 4270.9473188041. The cubic root of 18240991 is about 263.2385417870.

The spelling of 18240991 in words is "eighteen million, two hundred forty thousand, nine hundred ninety-one".