66731696640 has 1920 divisors, whose sum is σ = 312360364800. Its totient is φ = 13377208320.

The previous prime is 66731696639. The next prime is 66731696671. The reversal of 66731696640 is 4669613766.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1093962210 + ... + 1093962270.

It is an arithmetic number, because the mean of its divisors is an integer number (162687690).

Almost surely, 2^66731696640 is an apocalyptic number.

66731696640 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 66731696640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156180182400).

66731696640 is an abundant number, since it is smaller than the sum of its proper divisors (245628668160).

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

66731696640 is a wasteful number, since it uses less digits than its factorization.

66731696640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 5878656, while the sum is 54.

The spelling of 66731696640 in words is "sixty-six billion, seven hundred thirty-one million, six hundred ninety-six thousand, six hundred forty".