18221615 has 8 divisors (see below), whose sum is σ = 22224768. Its totient is φ = 14338080.

The previous prime is 18221611. The next prime is 18221629. The reversal of 18221615 is 51612281.

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

It is not a de Polignac number, because 18221615 - 2² = 18221611 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18221611) by changing a digit.

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, 29567 + ... + 30176.

It is an arithmetic number, because the mean of its divisors is an integer number (2778096).

Almost surely, 2^18221615 is an apocalyptic number.

18221615 is a deficient number, since it is larger than the sum of its proper divisors (4003153).

18221615 is an equidigital number, since it uses as much as digits as its factorization.

18221615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59809.

The product of its digits is 960, while the sum is 26.

The square root of 18221615 is about 4268.6783668953. The cubic root of 18221615 is about 263.1453027554.

Adding to 18221615 its reverse (51612281), we get a palindrome (69833896).

The spelling of 18221615 in words is "eighteen million, two hundred twenty-one thousand, six hundred fifteen".