851864861 has 2 divisors, whose sum is σ = 851864862. Its totient is φ = 851864860.

The previous prime is 851864807. The next prime is 851864891. The reversal of 851864861 is 168468158.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 439531225 + 412333636 = 20965^2 + 20306^2 .

It is a cyclic number.

It is not a de Polignac number, because 851864861 - 2¹⁴ = 851848477 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (851864891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 425932430 + 425932431.

It is an arithmetic number, because the mean of its divisors is an integer number (425932431).

Almost surely, 2^851864861 is an apocalyptic number.

It is an amenable number.

851864861 is a deficient number, since it is larger than the sum of its proper divisors (1).

851864861 is an equidigital number, since it uses as much as digits as its factorization.

851864861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 368640, while the sum is 47.

The square root of 851864861 is about 29186.7240539256. The cubic root of 851864861 is about 947.9604855286.

The spelling of 851864861 in words is "eight hundred fifty-one million, eight hundred sixty-four thousand, eight hundred sixty-one".