856391121 has 6 divisors (see below), whose sum is σ = 1237009410. Its totient is φ = 570927408.

The previous prime is 856391117. The next prime is 856391143. The reversal of 856391121 is 121193658.

856391121 is a `hidden beast` number, since 8 + 5 + 639 + 1 + 12 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 769230225 + 87160896 = 27735^2 + 9336^2 .

It is not a de Polignac number, because 856391121 - 2² = 856391117 is a prime.

It is not an unprimeable number, because it can be changed into a prime (856391101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 47577276 + ... + 47577293.

It is an arithmetic number, because the mean of its divisors is an integer number (206168235).

Almost surely, 2^856391121 is an apocalyptic number.

It is an amenable number.

856391121 is a deficient number, since it is larger than the sum of its proper divisors (380618289).

856391121 is a wasteful number, since it uses less digits than its factorization.

856391121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95154575 (or 95154572 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 856391121 is about 29264.1610335919. The cubic root of 856391121 is about 949.6364706964.

The spelling of 856391121 in words is "eight hundred fifty-six million, three hundred ninety-one thousand, one hundred twenty-one".