66991933584 has 45 divisors (see below), whose sum is σ = 187493062393. Its totient is φ = 22329609216.

The previous prime is 66991933553. The next prime is 66991933651. The reversal of 66991933584 is 48533919966.

The square root of 66991933584 is 258828.

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

66991933584 is a `hidden beast` number, since 6 + 6 + 9 + 9 + 19 + 33 + 584 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1783203984 + 65208729600 = 42228^2 + 255360^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3095152 + ... + 3116720.

Almost surely, 2^66991933584 is an apocalyptic number.

66991933584 is the 258828-th square number.

It is an amenable number.

66991933584 is an abundant number, since it is smaller than the sum of its proper divisors (120501128809).

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

66991933584 is an frugal number, since it uses more digits than its factorization.

66991933584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43152 (or 21574 counting only the distinct ones).

The product of its digits is 37791360, while the sum is 63.

The spelling of 66991933584 in words is "sixty-six billion, nine hundred ninety-one million, nine hundred thirty-three thousand, five hundred eighty-four".