18172281 has 4 divisors (see below), whose sum is σ = 24229712. Its totient is φ = 12114852.

The previous prime is 18172261. The next prime is 18172283. The reversal of 18172281 is 18227181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 18172281 - 2⁵ = 18172249 is a prime.

It is a super-2 number, since 2×18172281² = 660463593485922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18172283) 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, 3028711 + ... + 3028716.

It is an arithmetic number, because the mean of its divisors is an integer number (6057428).

Almost surely, 2^18172281 is an apocalyptic number.

It is an amenable number.

18172281 is a deficient number, since it is larger than the sum of its proper divisors (6057431).

18172281 is an equidigital number, since it uses as much as digits as its factorization.

18172281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6057430.

The product of its digits is 1792, while the sum is 30.

The square root of 18172281 is about 4262.8958467220. The cubic root of 18172281 is about 262.9076043947.

The spelling of 18172281 in words is "eighteen million, one hundred seventy-two thousand, two hundred eighty-one".