861851 has 8 divisors (see below), whose sum is σ = 902880. Its totient is φ = 821632.

The previous prime is 861829. The next prime is 861853. The reversal of 861851 is 158168.

861851 = T₉₅ + T₉₆ + ... + T₁₈₁.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861851 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (861853) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 3146 + ... + 3408.

It is an arithmetic number, because the mean of its divisors is an integer number (112860).

2⁸⁶¹⁸⁵¹ is an apocalyptic number.

861851 is a deficient number, since it is larger than the sum of its proper divisors (41029).

861851 is a wasteful number, since it uses less digits than its factorization.

861851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405.

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

The square root of 861851 is about 928.3593054416. The cubic root of 861851 is about 95.1650317045.

The spelling of 861851 in words is "eight hundred sixty-one thousand, eight hundred fifty-one".