66778814703216 has 640 divisors, whose sum is σ = 228354938634240. Its totient is φ = 16290539596800.

The previous prime is 66778814703193. The next prime is 66778814703247. The reversal of 66778814703216 is 61230741887766.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 18826841955 + ... + 18826845501.

It is an arithmetic number, because the mean of its divisors is an integer number (356804591616).

Almost surely, 2^{66778814703216} is an apocalyptic number.

66778814703216 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66778814703216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114177469317120).

66778814703216 is an abundant number, since it is smaller than the sum of its proper divisors (161576123931024).

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

66778814703216 is a wasteful number, since it uses less digits than its factorization.

66778814703216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5833 (or 5827 counting only the distinct ones).

The product of its (nonzero) digits is 113799168, while the sum is 66.

The spelling of 66778814703216 in words is "sixty-six trillion, seven hundred seventy-eight billion, eight hundred fourteen million, seven hundred three thousand, two hundred sixteen".