66221860 has 48 divisors (see below), whose sum is σ = 144310320. Its totient is φ = 25505280.

The previous prime is 66221789. The next prime is 66221861. The reversal of 66221860 is 6812266.

It can be written as a sum of positive squares in 8 ways, for example, as 1290496 + 64931364 = 1136^2 + 8058^2 .

It is not an unprimeable number, because it can be changed into a prime (66221861) 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, 80250 + ... + 81070.

It is an arithmetic number, because the mean of its divisors is an integer number (3006465).

Almost surely, 2^66221860 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66221860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72155160).

66221860 is an abundant number, since it is smaller than the sum of its proper divisors (78088460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66221860 is a wasteful number, since it uses less digits than its factorization.

66221860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 976 (or 974 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 66221860 is about 8137.6814879915. The cubic root of 66221860 is about 404.5763186026.

It can be divided in two parts, 66221 and 860, that added together give a square (67081 = 259²).

The spelling of 66221860 in words is "sixty-six million, two hundred twenty-one thousand, eight hundred sixty".