66881396736 has 1260 divisors, whose sum is σ = 270506561094. Its totient is φ = 16349921280.

The previous prime is 66881396731. The next prime is 66881396783. The reversal of 66881396736 is 63769318866.

It can be written as a sum of positive squares in only one way, i.e., 49177497600 + 17703899136 = 221760^2 + 133056^2 .

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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66881396731) by changing a digit.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 3934199800 + ... + 3934199816.

Almost surely, 2^66881396736 is an apocalyptic number.

66881396736 is a gapful number since it is divisible by the number (66) 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 66881396736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135253280547).

66881396736 is an abundant number, since it is smaller than the sum of its proper divisors (203625164358).

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

66881396736 is a wasteful number, since it uses less digits than its factorization.

66881396736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91 (or 40 counting only the distinct ones).

The product of its digits is 47029248, while the sum is 63.

The spelling of 66881396736 in words is "sixty-six billion, eight hundred eighty-one million, three hundred ninety-six thousand, seven hundred thirty-six".