856238129 has 2 divisors, whose sum is σ = 856238130. Its totient is φ = 856238128.

The previous prime is 856238093. The next prime is 856238143. The reversal of 856238129 is 921832658.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 537544225 + 318693904 = 23185^2 + 17852^2 .

It is a cyclic number.

It is not a de Polignac number, because 856238129 - 2⁸ = 856237873 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 856238129.

It is not a weakly prime, because it can be changed into another prime (856238179) 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 as a sum of consecutive naturals, namely, 428119064 + 428119065.

It is an arithmetic number, because the mean of its divisors is an integer number (428119065).

Almost surely, 2^856238129 is an apocalyptic number.

It is an amenable number.

856238129 is a deficient number, since it is larger than the sum of its proper divisors (1).

856238129 is an equidigital number, since it uses as much as digits as its factorization.

856238129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 207360, while the sum is 44.

The square root of 856238129 is about 29261.5469345009. The cubic root of 856238129 is about 949.5799173171.

The spelling of 856238129 in words is "eight hundred fifty-six million, two hundred thirty-eight thousand, one hundred twenty-nine".