857561 has 4 divisors (see below), whose sum is σ = 862692. Its totient is φ = 852432.

The previous prime is 857551. The next prime is 857567. The reversal of 857561 is 165758.

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 755161 + 102400 = 869^2 + 320^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-857561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (857567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2306 + ... + 2651.

It is an arithmetic number, because the mean of its divisors is an integer number (215673).

2⁸⁵⁷⁵⁶¹ is an apocalyptic number.

It is an amenable number.

857561 is a deficient number, since it is larger than the sum of its proper divisors (5131).

857561 is a wasteful number, since it uses less digits than its factorization.

857561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5130.

The product of its digits is 8400, while the sum is 32.

The square root of 857561 is about 926.0458951909. The cubic root of 857561 is about 95.0068693094.

The spelling of 857561 in words is "eight hundred fifty-seven thousand, five hundred sixty-one".