66816512 has 80 divisors (see below), whose sum is σ = 154906752. Its totient is φ = 28200960.

The previous prime is 66816509. The next prime is 66816523. The reversal of 66816512 is 21561866.

It is a happy number.

It is a super-2 number, since 2×66816512² = 8928892551692288, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 369062 + ... + 369242.

Almost surely, 2^66816512 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 66816512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (77453376).

66816512 is an abundant number, since it is smaller than the sum of its proper divisors (88090240).

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

66816512 is a wasteful number, since it uses less digits than its factorization.

66816512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309 (or 293 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 66816512 is about 8174.1367739964. The cubic root of 66816512 is about 405.7837022380.

The spelling of 66816512 in words is "sixty-six million, eight hundred sixteen thousand, five hundred twelve".