857666 has 4 divisors (see below), whose sum is σ = 1286502. Its totient is φ = 428832.

The previous prime is 857663. The next prime is 857669. The reversal of 857666 is 666758.

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

It is an interprime number because it is at equal distance from previous prime (857663) and next prime (857669).

It can be written as a sum of positive squares in only one way, i.e., 714025 + 143641 = 845^2 + 379^2 .

It is not an unprimeable number, because it can be changed into a prime (857663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 214415 + ... + 214418.

2⁸⁵⁷⁶⁶⁶ is an apocalyptic number.

857666 is a deficient number, since it is larger than the sum of its proper divisors (428836).

857666 is a wasteful number, since it uses less digits than its factorization.

857666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428835.

The product of its digits is 60480, while the sum is 38.

The square root of 857666 is about 926.1025861102. The cubic root of 857666 is about 95.0107467067.

The spelling of 857666 in words is "eight hundred fifty-seven thousand, six hundred sixty-six".