851861 has 4 divisors (see below), whose sum is σ = 856800. Its totient is φ = 846924.

The previous prime is 851843. The next prime is 851863. The reversal of 851861 is 168158.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 851861 - 2⁶ = 851797 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 851861.

It is not an unprimeable number, because it can be changed into a prime (851863) 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, 2201 + ... + 2558.

It is an arithmetic number, because the mean of its divisors is an integer number (214200).

2⁸⁵¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

851861 is a deficient number, since it is larger than the sum of its proper divisors (4939).

851861 is a wasteful number, since it uses less digits than its factorization.

851861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4938.

The product of its digits is 1920, while the sum is 29.

The square root of 851861 is about 922.9631628619. The cubic root of 851861 is about 94.7959053345.

The spelling of 851861 in words is "eight hundred fifty-one thousand, eight hundred sixty-one".