66544425720 has 80 divisors (see below), whose sum is σ = 223663219560. Its totient is φ = 17745179328.

The previous prime is 66544425707. The next prime is 66544425721. The reversal of 66544425720 is 2752444566.

66544425720 is a `hidden beast` number, since 66 + 544 + 4 + 25 + 7 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66544425721) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 10265962 + ... + 10272441.

Almost surely, 2^66544425720 is an apocalyptic number.

66544425720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66544425720 is an abundant number, since it is smaller than the sum of its proper divisors (157118793840).

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

66544425720 is a wasteful number, since it uses less digits than its factorization.

66544425720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20538426 (or 20538413 counting only the distinct ones).

The product of its (nonzero) digits is 1612800, while the sum is 45.

The spelling of 66544425720 in words is "sixty-six billion, five hundred forty-four million, four hundred twenty-five thousand, seven hundred twenty".