66517720 has 16 divisors (see below), whose sum is σ = 149664960. Its totient is φ = 26607072.

The previous prime is 66517663. The next prime is 66517729. The reversal of 66517720 is 2771566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66517729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 831432 + ... + 831511.

It is an arithmetic number, because the mean of its divisors is an integer number (9354060).

Almost surely, 2^66517720 is an apocalyptic number.

It is an amenable number.

66517720 is an abundant number, since it is smaller than the sum of its proper divisors (83147240).

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

66517720 is a wasteful number, since it uses less digits than its factorization.

66517720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1662954 (or 1662950 counting only the distinct ones).

The product of its (nonzero) digits is 17640, while the sum is 34.

The square root of 66517720 is about 8155.8396256915. The cubic root of 66517720 is about 405.1779332971.

The spelling of 66517720 in words is "sixty-six million, five hundred seventeen thousand, seven hundred twenty".