851808 has 48 divisors (see below), whose sum is σ = 2358720. Its totient is φ = 268416.

The previous prime is 851803. The next prime is 851813. The reversal of 851808 is 808158.

It is an interprime number because it is at equal distance from previous prime (851803) and next prime (851813).

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851801) by changing a digit.

851808 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1591 + ... + 2057.

It is an arithmetic number, because the mean of its divisors is an integer number (49140).

2⁸⁵¹⁸⁰⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 851808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1179360).

851808 is an abundant number, since it is smaller than the sum of its proper divisors (1506912).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

851808 is a wasteful number, since it uses less digits than its factorization.

851808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499 (or 491 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 30.

The square root of 851808 is about 922.9344505435. The cubic root of 851808 is about 94.7939393302.

The spelling of 851808 in words is "eight hundred fifty-one thousand, eight hundred eight".