18240491 has 4 divisors (see below), whose sum is σ = 18250800. Its totient is φ = 18230184.

The previous prime is 18240479. The next prime is 18240511. The reversal of 18240491 is 19404281.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 19404281 = 13 ⋅1492637.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18240491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18240401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1751 + ... + 6288.

It is an arithmetic number, because the mean of its divisors is an integer number (4562700).

Almost surely, 2^18240491 is an apocalyptic number.

18240491 is a deficient number, since it is larger than the sum of its proper divisors (10309).

18240491 is an equidigital number, since it uses as much as digits as its factorization.

18240491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10308.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 18240491 is about 4270.8887833799. Note that the first 3 decimals coincide. The cubic root of 18240491 is about 263.2361365728.

The spelling of 18240491 in words is "eighteen million, two hundred forty thousand, four hundred ninety-one".