66831680 has 42 divisors (see below), whose sum is σ = 159491934. Its totient is φ = 26674176.

The previous prime is 66831671. The next prime is 66831733. The reversal of 66831680 is 8613866.

It can be written as a sum of positive squares in 3 ways, for example, as 29767936 + 37063744 = 5456^2 + 6088^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 146012 + ... + 146468.

It is an arithmetic number, because the mean of its divisors is an integer number (3797427).

Almost surely, 2^66831680 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 66831680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79745967).

66831680 is an abundant number, since it is smaller than the sum of its proper divisors (92660254).

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

66831680 is an frugal number, since it uses more digits than its factorization.

66831680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 931 (or 464 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 38.

The square root of 66831680 is about 8175.0645257392. The cubic root of 66831680 is about 405.8144055344.

The spelling of 66831680 in words is "sixty-six million, eight hundred thirty-one thousand, six hundred eighty".