66545993521920 has 1152 divisors, whose sum is σ = 253923525918720. Its totient is φ = 14673125376000.

The previous prime is 66545993521919. The next prime is 66545993521961. The reversal of 66545993521920 is 2912539954566.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3159668190 + ... + 3159689250.

It is an arithmetic number, because the mean of its divisors is an integer number (220419727360).

Almost surely, 2^{66545993521920} is an apocalyptic number.

66545993521920 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 66545993521920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126961762959360).

66545993521920 is an abundant number, since it is smaller than the sum of its proper divisors (187377532396800).

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

66545993521920 is a wasteful number, since it uses less digits than its factorization.

66545993521920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21273 (or 21259 counting only the distinct ones).

The product of its (nonzero) digits is 157464000, while the sum is 66.

The spelling of 66545993521920 in words is "sixty-six trillion, five hundred forty-five billion, nine hundred ninety-three million, five hundred twenty-one thousand, nine hundred twenty".