66173257 has 8 divisors (see below), whose sum is σ = 70048800. Its totient is φ = 62337024.

The previous prime is 66173213. The next prime is 66173297. The reversal of 66173257 is 75237166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-66173257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66173297) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6328 + ... + 13129.

It is an arithmetic number, because the mean of its divisors is an integer number (8756100).

Almost surely, 2^66173257 is an apocalyptic number.

It is an amenable number.

66173257 is a deficient number, since it is larger than the sum of its proper divisors (3875543).

66173257 is a wasteful number, since it uses less digits than its factorization.

66173257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19655.

The product of its digits is 52920, while the sum is 37.

The square root of 66173257 is about 8134.6946470043. The cubic root of 66173257 is about 404.4773158693.

It can be divided in two parts, 66173 and 257, that added together give a triangular number (66430 = T₃₆₄).

The spelling of 66173257 in words is "sixty-six million, one hundred seventy-three thousand, two hundred fifty-seven".