18031491 has 40 divisors (see below), whose sum is σ = 28621824. Its totient is φ = 11294640.

The previous prime is 18031483. The next prime is 18031547. The reversal of 18031491 is 19413081.

It is not a de Polignac number, because 18031491 - 2³ = 18031483 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18031421) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 107890 + ... + 108056.

Almost surely, 2^18031491 is an apocalyptic number.

18031491 is a deficient number, since it is larger than the sum of its proper divisors (10590333).

18031491 is a wasteful number, since it uses less digits than its factorization.

18031491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 18031491 is about 4246.3503152708. The cubic root of 18031491 is about 262.2268832827.

The spelling of 18031491 in words is "eighteen million, thirty-one thousand, four hundred ninety-one".