666785173 has 4 divisors (see below), whose sum is σ = 683048268. Its totient is φ = 650522080.

The previous prime is 666785131. The next prime is 666785191. The reversal of 666785173 is 371587666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 49660209 + 617124964 = 7047^2 + 24842^2 .

It is a cyclic number.

It is not a de Polignac number, because 666785173 - 2⁹ = 666784661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666785573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8131486 + ... + 8131567.

It is an arithmetic number, because the mean of its divisors is an integer number (170762067).

Almost surely, 2^666785173 is an apocalyptic number.

It is an amenable number.

666785173 is a deficient number, since it is larger than the sum of its proper divisors (16263095).

666785173 is a wasteful number, since it uses less digits than its factorization.

666785173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16263094.

The product of its digits is 1270080, while the sum is 49.

The square root of 666785173 is about 25822.1837380188. The cubic root of 666785173 is about 873.6322240784.

The spelling of 666785173 in words is "six hundred sixty-six million, seven hundred eighty-five thousand, one hundred seventy-three".