66173856385 has 128 divisors (see below), whose sum is σ = 103604659200. Its totient is φ = 40284905472.

The previous prime is 66173856361. The next prime is 66173856389. The reversal of 66173856385 is 58365837166.

It is not a de Polignac number, because 66173856385 - 2⁷ = 66173856257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66173856389) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 80016342 + ... + 80017168.

It is an arithmetic number, because the mean of its divisors is an integer number (809411400).

Almost surely, 2^66173856385 is an apocalyptic number.

66173856385 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66173856385 is a deficient number, since it is larger than the sum of its proper divisors (37430802815).

66173856385 is a wasteful number, since it uses less digits than its factorization.

66173856385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1000 (or 986 counting only the distinct ones).

The product of its digits is 21772800, while the sum is 58.

The spelling of 66173856385 in words is "sixty-six billion, one hundred seventy-three million, eight hundred fifty-six thousand, three hundred eighty-five".