851640 has 64 divisors (see below), whose sum is σ = 2626560. Its totient is φ = 220800.

The previous prime is 851639. The next prime is 851647. The reversal of 851640 is 46158.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 851640.

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 851640.

It is not an unprimeable number, because it can be changed into a prime (851647) 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 15 ways as a sum of consecutive naturals, for example, 5565 + ... + 5715.

It is an arithmetic number, because the mean of its divisors is an integer number (41040).

2⁸⁵¹⁶⁴⁰ 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 851640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1313280).

851640 is an abundant number, since it is smaller than the sum of its proper divisors (1774920).

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

851640 is a wasteful number, since it uses less digits than its factorization.

851640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 851640 is about 922.8434320078. The cubic root of 851640 is about 94.7877069285.

Adding to 851640 its reverse (46158), we get a palindrome (897798).

The spelling of 851640 in words is "eight hundred fifty-one thousand, six hundred forty".