66899755440 has 640 divisors, whose sum is σ = 281981952000. Its totient is φ = 14237420544.

The previous prime is 66899755423. The next prime is 66899755441. The reversal of 66899755440 is 4455799866.

66899755440 is a `hidden beast` number, since 6 + 6 + 89 + 9 + 7 + 5 + 544 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (66899755441) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 16947547 + ... + 16951493.

It is an arithmetic number, because the mean of its divisors is an integer number (440596800).

Almost surely, 2^66899755440 is an apocalyptic number.

66899755440 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 66899755440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140990976000).

66899755440 is an abundant number, since it is smaller than the sum of its proper divisors (215082196560).

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

66899755440 is a wasteful number, since it uses less digits than its factorization.

66899755440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4054 (or 4042 counting only the distinct ones).

The product of its (nonzero) digits is 65318400, while the sum is 63.

The spelling of 66899755440 in words is "sixty-six billion, eight hundred ninety-nine million, seven hundred fifty-five thousand, four hundred forty".