66221665 has 8 divisors (see below), whose sum is σ = 79531200. Its totient is φ = 52933872.

The previous prime is 66221657. The next prime is 66221689. The reversal of 66221665 is 56612266.

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

It is a cyclic number.

It is not a de Polignac number, because 66221665 - 2³ = 66221657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66221665.

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, 2262 + ... + 11728.

It is an arithmetic number, because the mean of its divisors is an integer number (9941400).

Almost surely, 2^66221665 is an apocalyptic number.

It is an amenable number.

66221665 is a deficient number, since it is larger than the sum of its proper divisors (13309535).

66221665 is a wasteful number, since it uses less digits than its factorization.

66221665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10871.

The product of its digits is 25920, while the sum is 34.

The square root of 66221665 is about 8137.6695066831. The cubic root of 66221665 is about 404.5759214907.

The spelling of 66221665 in words is "sixty-six million, two hundred twenty-one thousand, six hundred sixty-five".