66221761 has 16 divisors (see below), whose sum is σ = 72264960. Its totient is φ = 60491200.

The previous prime is 66221759. The next prime is 66221767. The reversal of 66221761 is 16712266.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 66221761 - 2¹ = 66221759 is a prime.

It is a super-2 number, since 2×66221761² = 8770643259882242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66221767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66876 + ... + 67858.

It is an arithmetic number, because the mean of its divisors is an integer number (4516560).

Almost surely, 2^66221761 is an apocalyptic number.

It is an amenable number.

66221761 is a deficient number, since it is larger than the sum of its proper divisors (6043199).

66221761 is a wasteful number, since it uses less digits than its factorization.

66221761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1136.

The product of its digits is 6048, while the sum is 31.

The square root of 66221761 is about 8137.6754051756. The cubic root of 66221761 is about 404.5761169920.

The spelling of 66221761 in words is "sixty-six million, two hundred twenty-one thousand, seven hundred sixty-one".