66787971264 has 336 divisors, whose sum is σ = 235126914048. Its totient is φ = 17690517504.

The previous prime is 66787971241. The next prime is 66787971293. The reversal of 66787971264 is 46217978766.

66787971264 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 (336).

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4585177 + ... + 4599719.

Almost surely, 2^66787971264 is an apocalyptic number.

66787971264 is a gapful number since it is divisible by the number (64) 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 66787971264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117563457024).

66787971264 is an abundant number, since it is smaller than the sum of its proper divisors (168338942784).

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

66787971264 is a wasteful number, since it uses less digits than its factorization.

66787971264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14652 (or 14639 counting only the distinct ones).

The product of its digits is 42674688, while the sum is 63.

The spelling of 66787971264 in words is "sixty-six billion, seven hundred eighty-seven million, nine hundred seventy-one thousand, two hundred sixty-four".