18400531 has 6 divisors (see below), whose sum is σ = 19420332. Its totient is φ = 17431740.

The previous prime is 18400523. The next prime is 18400541. The reversal of 18400531 is 13500481.

It is not a de Polignac number, because 18400531 - 2³ = 18400523 is a prime.

It is a super-2 number, since 2×18400531² = 677159082163922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18400541) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25125 + ... + 25846.

It is an arithmetic number, because the mean of its divisors is an integer number (3236722).

Almost surely, 2^18400531 is an apocalyptic number.

18400531 is a deficient number, since it is larger than the sum of its proper divisors (1019801).

18400531 is an equidigital number, since it uses as much as digits as its factorization.

18400531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51009 (or 50990 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 18400531 is about 4289.5840124655. The cubic root of 18400531 is about 264.0037639117.

The spelling of 18400531 in words is "eighteen million, four hundred thousand, five hundred thirty-one".