221565665 has 8 divisors (see below), whose sum is σ = 266891328. Its totient is φ = 176577520.

The previous prime is 221565629. The next prime is 221565689. The reversal of 221565665 is 566565122.

It is a happy number.

221565665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 221565665 - 2¹⁰ = 221564641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82931 + ... + 85560.

It is an arithmetic number, because the mean of its divisors is an integer number (33361416).

Almost surely, 2^221565665 is an apocalyptic number.

It is an amenable number.

221565665 is a deficient number, since it is larger than the sum of its proper divisors (45325663).

221565665 is a wasteful number, since it uses less digits than its factorization.

221565665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168759.

The product of its digits is 108000, while the sum is 38.

The square root of 221565665 is about 14885.0819614808. The cubic root of 221565665 is about 605.1097540107.

The spelling of 221565665 in words is "two hundred twenty-one million, five hundred sixty-five thousand, six hundred sixty-five".