66555760 has 80 divisors (see below), whose sum is σ = 163418112. Its totient is φ = 25171200.

The previous prime is 66555743. The next prime is 66555763. The reversal of 66555760 is 6755566.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66555763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116275 + ... + 116845.

Almost surely, 2^66555760 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 66555760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81709056).

66555760 is an abundant number, since it is smaller than the sum of its proper divisors (96862352).

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

66555760 is a wasteful number, since it uses less digits than its factorization.

66555760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 662 (or 656 counting only the distinct ones).

The product of its (nonzero) digits is 189000, while the sum is 40.

The square root of 66555760 is about 8158.1713637310. The cubic root of 66555760 is about 405.2551559850.

The spelling of 66555760 in words is "sixty-six million, five hundred fifty-five thousand, seven hundred sixty".