851220 has 36 divisors (see below), whose sum is σ = 2582580. Its totient is φ = 226944.

The previous prime is 851209. The next prime is 851231. The reversal of 851220 is 22158.

It is an interprime number because it is at equal distance from previous prime (851209) and next prime (851231).

It can be written as a sum of positive squares in 2 ways, for example, as 125316 + 725904 = 354^2 + 852^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 851193 and 851202.

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 851220.

It is an unprimeable number.

851220 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 11 ways as a sum of consecutive naturals, for example, 2185 + ... + 2544.

2⁸⁵¹²²⁰ is an apocalyptic number.

It is an amenable number.

851220 is an abundant number, since it is smaller than the sum of its proper divisors (1731360).

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

851220 is a wasteful number, since it uses less digits than its factorization.

851220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4744 (or 4739 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 851220 is about 922.6158463846. The cubic root of 851220 is about 94.7721223375.

Adding to 851220 its reverse (22158), we get a palindrome (873378).

The spelling of 851220 in words is "eight hundred fifty-one thousand, two hundred twenty".