18221965 has 8 divisors (see below), whose sum is σ = 21903768. Its totient is φ = 14552640.

The previous prime is 18221953. The next prime is 18221989. The reversal of 18221965 is 56912281.

It can be written as a sum of positive squares in 4 ways, for example, as 133956 + 18088009 = 366^2 + 4253^2 .

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

It is not a de Polignac number, because 18221965 - 2⁷ = 18221837 is a prime.

It is a super-2 number, since 2×18221965² = 664080016922450, which contains 22 as substring.

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 18221965.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 475 + ... + 6055.

It is an arithmetic number, because the mean of its divisors is an integer number (2737971).

Almost surely, 2^18221965 is an apocalyptic number.

It is an amenable number.

18221965 is a deficient number, since it is larger than the sum of its proper divisors (3681803).

18221965 is an equidigital number, since it uses as much as digits as its factorization.

18221965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6239.

The product of its digits is 8640, while the sum is 34.

The square root of 18221965 is about 4268.7193629940. The cubic root of 18221965 is about 263.1469875725.

The spelling of 18221965 in words is "eighteen million, two hundred twenty-one thousand, nine hundred sixty-five".