999990851 has 2 divisors, whose sum is σ = 999990852. Its totient is φ = 999990850.

The previous prime is 999990841. The next prime is 999990853. The reversal of 999990851 is 158099999.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 999990851 - 2⁶ = 999990787 is a prime.

It is a super-3 number, since 3×999990851³ (a number of 28 digits) contains 333 as substring.

It is a Sophie Germain prime.

Together with 999990853, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (999990853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499995425 + 499995426.

It is an arithmetic number, because the mean of its divisors is an integer number (499995426).

Almost surely, 2^999990851 is an apocalyptic number.

999990851 is a deficient number, since it is larger than the sum of its proper divisors (1).

999990851 is an equidigital number, since it uses as much as digits as its factorization.

999990851 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2361960, while the sum is 59.

The square root of 999990851 is about 31622.6319429614. The cubic root of 999990851 is about 999.9969503240.

The spelling of 999990851 in words is "nine hundred ninety-nine million, nine hundred ninety thousand, eight hundred fifty-one".