66565811287944 has 128 divisors (see below), whose sum is σ = 186287143680000. Its totient is φ = 22023267840000.

The previous prime is 66565811287919. The next prime is 66565811287967. The reversal of 66565811287944 is 44978211856566.

66565811287944 is a `hidden beast` number, since 6 + 6 + 565 + 8 + 1 + 12 + 8 + 7 + 9 + 44 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16727194 + ... + 20320694.

It is an arithmetic number, because the mean of its divisors is an integer number (1455368310000).

Almost surely, 2^{66565811287944} 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 66565811287944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93143571840000).

66565811287944 is an abundant number, since it is smaller than the sum of its proper divisors (119721332392056).

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

66565811287944 is a wasteful number, since it uses less digits than its factorization.

66565811287944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3594156 (or 3594146 counting only the distinct ones).

The product of its digits is 696729600, while the sum is 72.

The spelling of 66565811287944 in words is "sixty-six trillion, five hundred sixty-five billion, eight hundred eleven million, two hundred eighty-seven thousand, nine hundred forty-four".