999916861 has 2 divisors, whose sum is σ = 999916862. Its totient is φ = 999916860.

The previous prime is 999916859. The next prime is 999916871. The reversal of 999916861 is 168619999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 985332100 + 14584761 = 31390^2 + 3819^2 .

It is a cyclic number.

It is not a de Polignac number, because 999916861 - 2¹ = 999916859 is a prime.

Together with 999916859, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 999916796 and 999916805.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999916871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499958430 + 499958431.

It is an arithmetic number, because the mean of its divisors is an integer number (499958431).

Almost surely, 2^999916861 is an apocalyptic number.

It is an amenable number.

999916861 is a deficient number, since it is larger than the sum of its proper divisors (1).

999916861 is an equidigital number, since it uses as much as digits as its factorization.

999916861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1889568, while the sum is 58.

The square root of 999916861 is about 31621.4620313483. The cubic root of 999916861 is about 999.9722862320.

The spelling of 999916861 in words is "nine hundred ninety-nine million, nine hundred sixteen thousand, eight hundred sixty-one".