66217860 has 72 divisors (see below), whose sum is σ = 207357696. Its totient is φ = 17087040.

The previous prime is 66217841. The next prime is 66217861. The reversal of 66217860 is 6871266.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (66217861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 354 + ... + 11513.

It is an arithmetic number, because the mean of its divisors is an integer number (2879968).

Almost surely, 2^66217860 is an apocalyptic number.

66217860 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66217860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103678848).

66217860 is an abundant number, since it is smaller than the sum of its proper divisors (141139836).

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

66217860 is a wasteful number, since it uses less digits than its factorization.

66217860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11913 (or 11908 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 66217860 is about 8137.4357140318. The cubic root of 66217860 is about 404.5681725621.

The spelling of 66217860 in words is "sixty-six million, two hundred seventeen thousand, eight hundred sixty".