856981 has 4 divisors (see below), whose sum is σ = 866700. Its totient is φ = 847264.

The previous prime is 856969. The next prime is 856993. The reversal of 856981 is 189658.

856981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (856969) and next prime (856993).

It can be written as a sum of positive squares in 2 ways, for example, as 576081 + 280900 = 759^2 + 530^2 .

It is a cyclic number.

It is not a de Polignac number, because 856981 - 2⁵ = 856949 is a prime.

It is a super-2 number, since 2×856981² = 1468832868722, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

856981 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 856981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (856901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4726 + ... + 4903.

It is an arithmetic number, because the mean of its divisors is an integer number (216675).

2⁸⁵⁶⁹⁸¹ is an apocalyptic number.

It is an amenable number.

856981 is a deficient number, since it is larger than the sum of its proper divisors (9719).

856981 is an equidigital number, since it uses as much as digits as its factorization.

856981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9718.

The product of its digits is 17280, while the sum is 37.

The square root of 856981 is about 925.7326827978. The cubic root of 856981 is about 94.9854456004.

The spelling of 856981 in words is "eight hundred fifty-six thousand, nine hundred eighty-one".