856643387 has 2 divisors, whose sum is σ = 856643388. Its totient is φ = 856643386.

The previous prime is 856643371. The next prime is 856643407. The reversal of 856643387 is 783346658.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 856643387 - 2⁴ = 856643371 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (856643087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428321693 + 428321694.

It is an arithmetic number, because the mean of its divisors is an integer number (428321694).

Almost surely, 2^856643387 is an apocalyptic number.

856643387 is a deficient number, since it is larger than the sum of its proper divisors (1).

856643387 is an equidigital number, since it uses as much as digits as its factorization.

856643387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2903040, while the sum is 50.

The square root of 856643387 is about 29268.4708688377. The cubic root of 856643387 is about 949.7297059287.

The spelling of 856643387 in words is "eight hundred fifty-six million, six hundred forty-three thousand, three hundred eighty-seven".