18218251 has 8 divisors (see below), whose sum is σ = 18547200. Its totient is φ = 17892072.

The previous prime is 18218209. The next prime is 18218257. The reversal of 18218251 is 15281281.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18218251 - 2¹⁵ = 18185483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18218257) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15966 + ... + 17068.

It is an arithmetic number, because the mean of its divisors is an integer number (2318400).

Almost surely, 2^18218251 is an apocalyptic number.

18218251 is the 2700-th centered pentagonal number.

18218251 is a deficient number, since it is larger than the sum of its proper divisors (328949).

18218251 is a wasteful number, since it uses less digits than its factorization.

18218251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1385.

The product of its digits is 1280, while the sum is 28.

The square root of 18218251 is about 4268.2843157409. The cubic root of 18218251 is about 263.1291081557.

The spelling of 18218251 in words is "eighteen million, two hundred eighteen thousand, two hundred fifty-one".