66979680 has 96 divisors (see below), whose sum is σ = 220195584. Its totient is φ = 17081856.

The previous prime is 66979667. The next prime is 66979721. The reversal of 66979680 is 8697966.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8007 + ... + 14073.

It is an arithmetic number, because the mean of its divisors is an integer number (2293704).

Almost surely, 2^66979680 is an apocalyptic number.

66979680 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 66979680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110097792).

66979680 is an abundant number, since it is smaller than the sum of its proper divisors (153215904).

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

66979680 is a wasteful number, since it uses less digits than its factorization.

66979680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6108 (or 6100 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 51.

The square root of 66979680 is about 8184.1114361915. Note that the first 3 decimals coincide. The cubic root of 66979680 is about 406.1137458644.

The spelling of 66979680 in words is "sixty-six million, nine hundred seventy-nine thousand, six hundred eighty".