851605 has 8 divisors (see below), whose sum is σ = 1028664. Its totient is φ = 676800.

The previous prime is 851603. The next prime is 851623. The reversal of 851605 is 506158.

It can be written as a sum of positive squares in 4 ways, for example, as 1521 + 850084 = 39^2 + 922^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 851605 - 2¹ = 851603 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 851605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851603) 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 7 ways as a sum of consecutive naturals, for example, 435 + ... + 1375.

It is an arithmetic number, because the mean of its divisors is an integer number (128583).

2⁸⁵¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

851605 is a deficient number, since it is larger than the sum of its proper divisors (177059).

851605 is a wasteful number, since it uses less digits than its factorization.

851605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 851605 is about 922.8244686830. The cubic root of 851605 is about 94.7864084083.

The spelling of 851605 in words is "eight hundred fifty-one thousand, six hundred five".