66778891612800 has 384 divisors, whose sum is σ = 220786361625600. Its totient is φ = 17740341964800.

The previous prime is 66778891612787. The next prime is 66778891612813. The reversal of 66778891612800 is 821619887766.

It is an interprime number because it is at equal distance from previous prime (66778891612787) and next prime (66778891612813).

It is a tau number, because it is divible by the number of its divisors (384).

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, 3314572327 + ... + 3314592473.

It is an arithmetic number, because the mean of its divisors is an integer number (574964483400).

Almost surely, 2^{66778891612800} is an apocalyptic number.

66778891612800 is a gapful number since it is divisible by the number (60) 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 66778891612800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110393180812800).

66778891612800 is an abundant number, since it is smaller than the sum of its proper divisors (154007470012800).

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

66778891612800 is a wasteful number, since it uses less digits than its factorization.

66778891612800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21464 (or 21447 counting only the distinct ones).

The product of its (nonzero) digits is 97542144, while the sum is 69.

The spelling of 66778891612800 in words is "sixty-six trillion, seven hundred seventy-eight billion, eight hundred ninety-one million, six hundred twelve thousand, eight hundred".