18512221 has 8 divisors (see below), whose sum is σ = 22784384. Its totient is φ = 14646960.

The previous prime is 18512203. The next prime is 18512227. The reversal of 18512221 is 12221581.

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 18512221 - 2¹⁵ = 18479453 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18512192 and 18512201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18512227) 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, 101625 + ... + 101806.

It is an arithmetic number, because the mean of its divisors is an integer number (2848048).

Almost surely, 2^18512221 is an apocalyptic number.

It is an amenable number.

18512221 is a deficient number, since it is larger than the sum of its proper divisors (4272163).

18512221 is a wasteful number, since it uses less digits than its factorization.

18512221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203451.

The product of its digits is 320, while the sum is 22.

The square root of 18512221 is about 4302.5830613714. The cubic root of 18512221 is about 264.5368485320.

The spelling of 18512221 in words is "eighteen million, five hundred twelve thousand, two hundred twenty-one".