18236731 has 4 divisors (see below), whose sum is σ = 18398232. Its totient is φ = 18075232.

The previous prime is 18236719. The next prime is 18236741. The reversal of 18236731 is 13763281.

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 18236731 - 2²³ = 9848123 is a prime.

It is a super-2 number, since 2×18236731² = 665156715132722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18236693 and 18236702.

It is not an unprimeable number, because it can be changed into a prime (18236741) 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, 80581 + ... + 80806.

It is an arithmetic number, because the mean of its divisors is an integer number (4599558).

Almost surely, 2^18236731 is an apocalyptic number.

18236731 is a deficient number, since it is larger than the sum of its proper divisors (161501).

18236731 is a wasteful number, since it uses less digits than its factorization.

18236731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161500.

The product of its digits is 6048, while the sum is 31.

The square root of 18236731 is about 4270.4485712862. The cubic root of 18236731 is about 263.2180479536.

The spelling of 18236731 in words is "eighteen million, two hundred thirty-six thousand, seven hundred thirty-one".