221621165 has 8 divisors (see below), whose sum is σ = 266171928. Its totient is φ = 177145920.

The previous prime is 221621119. The next prime is 221621177. The reversal of 221621165 is 561126122.

It can be written as a sum of positive squares in 4 ways, for example, as 21058921 + 200562244 = 4589^2 + 14162^2 .

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

It is not a de Polignac number, because 221621165 - 2⁸ = 221620909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12206 + ... + 24335.

It is an arithmetic number, because the mean of its divisors is an integer number (33271491).

Almost surely, 2^221621165 is an apocalyptic number.

It is an amenable number.

221621165 is a deficient number, since it is larger than the sum of its proper divisors (44550763).

221621165 is a wasteful number, since it uses less digits than its factorization.

221621165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37759.

The product of its digits is 1440, while the sum is 26.

The square root of 221621165 is about 14886.9461273963. The cubic root of 221621165 is about 605.1602744552.

Adding to 221621165 its reverse (561126122), we get a palindrome (782747287).

The spelling of 221621165 in words is "two hundred twenty-one million, six hundred twenty-one thousand, one hundred sixty-five".