999857851 has 2 divisors, whose sum is σ = 999857852. Its totient is φ = 999857850.

The previous prime is 999857809. The next prime is 999857897. The reversal of 999857851 is 158758999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 999857851 - 2²⁵ = 966303419 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 999857851.

It is not a weakly prime, because it can be changed into another prime (999857051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499928925 + 499928926.

It is an arithmetic number, because the mean of its divisors is an integer number (499928926).

Almost surely, 2^999857851 is an apocalyptic number.

999857851 is a deficient number, since it is larger than the sum of its proper divisors (1).

999857851 is an equidigital number, since it uses as much as digits as its factorization.

999857851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8164800, while the sum is 61.

The square root of 999857851 is about 31620.5289487700. The cubic root of 999857851 is about 999.9526147547.

The spelling of 999857851 in words is "nine hundred ninety-nine million, eight hundred fifty-seven thousand, eight hundred fifty-one".