66861644664384 has 224 divisors, whose sum is σ = 201713418142080. Its totient is φ = 21981907215360.

The previous prime is 66861644664343. The next prime is 66861644664413. The reversal of 66861644664384 is 48346644616866.

66861644664384 is a `hidden beast` number, since 6 + 6 + 8 + 61 + 6 + 446 + 6 + 43 + 84 = 666.

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

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

It is a nude number because it is divisible by every one of its digits.

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, 6945799 + ... + 13489529.

Almost surely, 2^{66861644664384} is an apocalyptic number.

66861644664384 is a gapful number since it is divisible by the number (64) 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 66861644664384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100856709071040).

66861644664384 is an abundant number, since it is smaller than the sum of its proper divisors (134851773477696).

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

66861644664384 is an frugal number, since it uses more digits than its factorization.

66861644664384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6543837 (or 6543809 counting only the distinct ones).

The product of its digits is 2293235712, while the sum is 72.

The spelling of 66861644664384 in words is "sixty-six trillion, eight hundred sixty-one billion, six hundred forty-four million, six hundred sixty-four thousand, three hundred eighty-four".