18400231 has 4 divisors (see below), whose sum is σ = 18411912. Its totient is φ = 18388552.

The previous prime is 18400177. The next prime is 18400237. The reversal of 18400231 is 13200481.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18400231 is a prime.

It is a super-2 number, since 2×18400231² = 677137001706722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18400199 and 18400208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18400237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3025 + ... + 6778.

It is an arithmetic number, because the mean of its divisors is an integer number (4602978).

Almost surely, 2^18400231 is an apocalyptic number.

18400231 is a deficient number, since it is larger than the sum of its proper divisors (11681).

18400231 is an equidigital number, since it uses as much as digits as its factorization.

18400231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11680.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 18400231 is about 4289.5490438973. The cubic root of 18400231 is about 264.0023291423.

The spelling of 18400231 in words is "eighteen million, four hundred thousand, two hundred thirty-one".