18018431 has 4 divisors (see below), whose sum is σ = 18148200. Its totient is φ = 17888664.

The previous prime is 18018401. The next prime is 18018433. The reversal of 18018431 is 13481081.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18018431 - 2¹⁸ = 17756287 is a prime.

It is a super-2 number, since 2×18018431² = 649327711403522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18018431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18018433) 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, 64676 + ... + 64953.

It is an arithmetic number, because the mean of its divisors is an integer number (4537050).

Almost surely, 2^18018431 is an apocalyptic number.

18018431 is a deficient number, since it is larger than the sum of its proper divisors (129769).

18018431 is a wasteful number, since it uses less digits than its factorization.

18018431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129768.

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 18018431 is about 4244.8122455534. The cubic root of 18018431 is about 262.1635586941.

The spelling of 18018431 in words is "eighteen million, eighteen thousand, four hundred thirty-one".