66716823616 has 63 divisors (see below), whose sum is σ = 134350861981. Its totient is φ = 32871782144.

The previous prime is 66716823601. The next prime is 66716823617. The reversal of 66716823616 is 61632861766.

The square root of 66716823616 is 258296.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 15749246016 + 50967577600 = 125496^2 + 225760^2 .

It is a super-2 number, since 2×66716823616² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66716823617) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 171508350 + ... + 171508738.

Almost surely, 2^66716823616 is an apocalyptic number.

66716823616 is the 258296-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66716823616

66716823616 is an abundant number, since it is smaller than the sum of its proper divisors (67634038365).

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

66716823616 is an frugal number, since it uses more digits than its factorization.

66716823616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 956 (or 474 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 52.

The spelling of 66716823616 in words is "sixty-six billion, seven hundred sixteen million, eight hundred twenty-three thousand, six hundred sixteen".