66991895520 has 192 divisors, whose sum is σ = 230385254400. Its totient is φ = 16227993600.

The previous prime is 66991895519. The next prime is 66991895533. The reversal of 66991895520 is 2559819966.

66991895520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (60).

It is a congruent number.

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, 8174625 + ... + 8182815.

It is an arithmetic number, because the mean of its divisors is an integer number (1199923200).

Almost surely, 2^66991895520 is an apocalyptic number.

66991895520 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 66991895520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115192627200).

66991895520 is an abundant number, since it is smaller than the sum of its proper divisors (163393358880).

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

66991895520 is a wasteful number, since it uses less digits than its factorization.

66991895520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9769 (or 9761 counting only the distinct ones).

The product of its (nonzero) digits is 10497600, while the sum is 60.

The spelling of 66991895520 in words is "sixty-six billion, nine hundred ninety-one million, eight hundred ninety-five thousand, five hundred twenty".