851816 has 48 divisors (see below), whose sum is σ = 1939140. Its totient is φ = 349440.

The previous prime is 851813. The next prime is 851821. The reversal of 851816 is 618158.

851816 = T₁₈₃ + T₁₈₄ + ... + T₂₂₃.

It can be written as a sum of positive squares in 2 ways, for example, as 828100 + 23716 = 910^2 + 154^2 .

It is not an unprimeable number, because it can be changed into a prime (851813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16046 + ... + 16098.

2⁸⁵¹⁸¹⁶ 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 851816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (969570).

851816 is an abundant number, since it is smaller than the sum of its proper divisors (1087324).

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

851816 is a wasteful number, since it uses less digits than its factorization.

851816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 103 counting only the distinct ones).

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

The square root of 851816 is about 922.9387845356. The cubic root of 851816 is about 94.7942360908.

The spelling of 851816 in words is "eight hundred fifty-one thousand, eight hundred sixteen".