66720 has 48 divisors (see below), whose sum is σ = 211680. Its totient is φ = 17664.

The previous prime is 66713. The next prime is 66721. The reversal of 66720 is 2766.

It is a tau number, because it is divible by the number of its divisors (48).

It is not an unprimeable number, because it can be changed into a prime (66721) by changing a digit.

66720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 411 + ... + 549.

It is an arithmetic number, because the mean of its divisors is an integer number (4410).

2⁶⁶⁷²⁰ is an apocalyptic number.

66720 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 66720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105840).

66720 is an abundant number, since it is smaller than the sum of its proper divisors (144960).

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

66720 is a wasteful number, since it uses less digits than its factorization.

66720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 66720 is about 258.3021486554. The cubic root of 66720 is about 40.5588232252.

The spelling of 66720 in words is "sixty-six thousand, seven hundred twenty".