18240493 has 4 divisors (see below), whose sum is σ = 18828928. Its totient is φ = 17652060.

The previous prime is 18240479. The next prime is 18240511. The reversal of 18240493 is 39404281.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18240493 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31), and also a Moran number because the ratio is a prime number: 588403 = 18240493 / (1 + 8 + 2 + 4 + 0 + 4 + 9 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18240413) 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, 294171 + ... + 294232.

It is an arithmetic number, because the mean of its divisors is an integer number (4707232).

Almost surely, 2^18240493 is an apocalyptic number.

It is an amenable number.

18240493 is a deficient number, since it is larger than the sum of its proper divisors (588435).

18240493 is an equidigital number, since it uses as much as digits as its factorization.

18240493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 588434.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 18240493 is about 4270.8890175232. The cubic root of 18240493 is about 263.2361461938.

The spelling of 18240493 in words is "eighteen million, two hundred forty thousand, four hundred ninety-three".