18008257 has 4 divisors (see below), whose sum is σ = 18956080. Its totient is φ = 17060436.

The previous prime is 18008231. The next prime is 18008279. The reversal of 18008257 is 75280081.

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 a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18008257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18008657) 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, 473883 + ... + 473920.

It is an arithmetic number, because the mean of its divisors is an integer number (4739020).

Almost surely, 2^18008257 is an apocalyptic number.

It is an amenable number.

18008257 is a deficient number, since it is larger than the sum of its proper divisors (947823).

18008257 is an equidigital number, since it uses as much as digits as its factorization.

18008257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 947822.

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 18008257 is about 4243.6136723316. The cubic root of 18008257 is about 262.1142063722.

The spelling of 18008257 in words is "eighteen million, eight thousand, two hundred fifty-seven".