999999863 has 4 divisors (see below), whose sum is σ = 1000064688. Its totient is φ = 999935040.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999863 is 368999999.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 368999999 = 2459 ⋅150061.

It is a cyclic number.

It is not a de Polignac number, because 999999863 - 2⁸ = 999999607 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999999883) 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 in 3 ways as a sum of consecutive naturals, for example, 5543 + ... + 45063.

It is an arithmetic number, because the mean of its divisors is an integer number (250016172).

Almost surely, 2^999999863 is an apocalyptic number.

999999863 is a deficient number, since it is larger than the sum of its proper divisors (64825).

999999863 is a wasteful number, since it uses less digits than its factorization.

999999863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64824.

The product of its digits is 76527504, while the sum is 71.

The square root of 999999863 is about 31622.7744355235. The cubic root of 999999863 is about 999.9999543333. Note that the first 4 decimals are identical.

The spelling of 999999863 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred sixty-three".