18149221 has 4 divisors (see below), whose sum is σ = 18196992. Its totient is φ = 18101452.

The previous prime is 18149213. The next prime is 18149239. The reversal of 18149221 is 12294181.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12294181 = 719 ⋅17099.

It is a cyclic number.

It is not a de Polignac number, because 18149221 - 2³ = 18149213 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18149221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18149821) 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, 23311 + ... + 24076.

It is an arithmetic number, because the mean of its divisors is an integer number (4549248).

Almost surely, 2^18149221 is an apocalyptic number.

It is an amenable number.

18149221 is a deficient number, since it is larger than the sum of its proper divisors (47771).

18149221 is an equidigital number, since it uses as much as digits as its factorization.

18149221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47770.

The product of its digits is 1152, while the sum is 28.

The square root of 18149221 is about 4260.1902539675. The cubic root of 18149221 is about 262.7963504177.

The spelling of 18149221 in words is "eighteen million, one hundred forty-nine thousand, two hundred twenty-one".