66816400 has 120 divisors (see below), whose sum is σ = 187587200. Its totient is φ = 22861440.

The previous prime is 66816397. The next prime is 66816427. The reversal of 66816400 is 461866.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 136957 + ... + 137443.

Almost surely, 2^66816400 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 66816400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93793600).

66816400 is an abundant number, since it is smaller than the sum of its proper divisors (120770800).

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

66816400 is a wasteful number, since it uses less digits than its factorization.

66816400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526 (or 501 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 66816400 is about 8174.1299231172. The cubic root of 66816400 is about 405.7834755087.

The spelling of 66816400 in words is "sixty-six million, eight hundred sixteen thousand, four hundred".