66147217920 has 800 divisors, whose sum is σ = 273312864000. Its totient is φ = 14977695744.

The previous prime is 66147217901. The next prime is 66147217943. The reversal of 66147217920 is 2971274166.

66147217920 is a `hidden beast` number, since 6 + 6 + 1 + 472 + 179 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 288852366 + ... + 288852594.

It is an arithmetic number, because the mean of its divisors is an integer number (341641080).

Almost surely, 2^66147217920 is an apocalyptic number.

66147217920 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 66147217920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136656432000).

66147217920 is an abundant number, since it is smaller than the sum of its proper divisors (207165646080).

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

66147217920 is a wasteful number, since it uses less digits than its factorization.

66147217920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 470 (or 445 counting only the distinct ones).

The product of its (nonzero) digits is 254016, while the sum is 45.

The spelling of 66147217920 in words is "sixty-six billion, one hundred forty-seven million, two hundred seventeen thousand, nine hundred twenty".