66399407256 has 192 divisors, whose sum is σ = 209902855680. Its totient is φ = 17347841280.

The previous prime is 66399407213. The next prime is 66399407281. The reversal of 66399407256 is 65270499366.

It is a junction number, because it is equal to n+sod(n) for n = 66399407196 and 66399407205.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1615521 + ... + 1656111.

It is an arithmetic number, because the mean of its divisors is an integer number (1093244040).

Almost surely, 2^66399407256 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 66399407256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104951427840).

66399407256 is an abundant number, since it is smaller than the sum of its proper divisors (143503448424).

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

66399407256 is a wasteful number, since it uses less digits than its factorization.

66399407256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40734 (or 40723 counting only the distinct ones).

The product of its (nonzero) digits is 14696640, while the sum is 57.

The spelling of 66399407256 in words is "sixty-six billion, three hundred ninety-nine million, four hundred seven thousand, two hundred fifty-six".