66631438720 has 384 divisors, whose sum is σ = 203255114400. Its totient is φ = 20654161920.

The previous prime is 66631438703. The next prime is 66631438723. The reversal of 66631438720 is 2783413666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66631438723) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 80375266 + ... + 80376094.

Almost surely, 2^66631438720 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 66631438720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101627557200).

66631438720 is an abundant number, since it is smaller than the sum of its proper divisors (136623675680).

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

66631438720 is a wasteful number, since it uses less digits than its factorization.

66631438720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106 (or 1087 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 46.

The spelling of 66631438720 in words is "sixty-six billion, six hundred thirty-one million, four hundred thirty-eight thousand, seven hundred twenty".