18220231 has 4 divisors (see below), whose sum is σ = 18322200. Its totient is φ = 18118264.

The previous prime is 18220193. The next prime is 18220247. The reversal of 18220231 is 13202281.

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 18220231 - 2¹⁹ = 17695943 is a prime.

It is a super-2 number, since 2×18220231² = 663953635386722, 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 = 18220199 and 18220208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18220271) 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, 50716 + ... + 51073.

It is an arithmetic number, because the mean of its divisors is an integer number (4580550).

Almost surely, 2^18220231 is an apocalyptic number.

18220231 is a deficient number, since it is larger than the sum of its proper divisors (101969).

18220231 is a wasteful number, since it uses less digits than its factorization.

18220231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101968.

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

The square root of 18220231 is about 4268.5162527511. The cubic root of 18220231 is about 263.1386402958.

The spelling of 18220231 in words is "eighteen million, two hundred twenty thousand, two hundred thirty-one".