66144720 has 80 divisors (see below), whose sum is σ = 206236800. Its totient is φ = 17536512.

The previous prime is 66144713. The next prime is 66144721. The reversal of 66144720 is 2744166.

66144720 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 (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66144721) 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, 46581 + ... + 47979.

It is an arithmetic number, because the mean of its divisors is an integer number (2577960).

Almost surely, 2^66144720 is an apocalyptic number.

66144720 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 66144720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103118400).

66144720 is an abundant number, since it is smaller than the sum of its proper divisors (140092080).

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

66144720 is a wasteful number, since it uses less digits than its factorization.

66144720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1612 (or 1606 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 30.

The square root of 66144720 is about 8132.9404276682. The cubic root of 66144720 is about 404.4191643374.

Adding to 66144720 its reverse (2744166), we get a palindrome (68888886).

The spelling of 66144720 in words is "sixty-six million, one hundred forty-four thousand, seven hundred twenty".