66221961 has 16 divisors (see below), whose sum is σ = 95472384. Its totient is φ = 40587264.

The previous prime is 66221959. The next prime is 66221977. The reversal of 66221961 is 16912266.

It is not a de Polignac number, because 66221961 - 2¹ = 66221959 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66221951) 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, 6720 + ... + 13326.

It is an arithmetic number, because the mean of its divisors is an integer number (5967024).

Almost surely, 2^66221961 is an apocalyptic number.

It is an amenable number.

66221961 is a deficient number, since it is larger than the sum of its proper divisors (29250423).

66221961 is a wasteful number, since it uses less digits than its factorization.

66221961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6880.

The product of its digits is 7776, while the sum is 33.

The square root of 66221961 is about 8137.6876936879. The cubic root of 66221961 is about 404.5765242858.

The spelling of 66221961 in words is "sixty-six million, two hundred twenty-one thousand, nine hundred sixty-one".