66661760 has 128 divisors (see below), whose sum is σ = 184407840. Its totient is φ = 22773760.

The previous prime is 66661741. The next prime is 66661769. The reversal of 66661760 is 6716666.

It is a happy number.

66661760 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66661769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119402 + ... + 119958.

Almost surely, 2^66661760 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 66661760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92203920).

66661760 is an abundant number, since it is smaller than the sum of its proper divisors (117746080).

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

66661760 is a wasteful number, since it uses less digits than its factorization.

66661760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 604 (or 592 counting only the distinct ones).

The product of its (nonzero) digits is 54432, while the sum is 38.

The square root of 66661760 is about 8164.6653330066. The cubic root of 66661760 is about 405.4701850149.

It can be divided in two parts, 666 and 61760, that added together give a palindrome (62426).

The spelling of 66661760 in words is "sixty-six million, six hundred sixty-one thousand, seven hundred sixty".