999999864 has 32 divisors (see below), whose sum is σ = 2777778000. Its totient is φ = 333333216.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999864 is 468999999.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a nude number because it is divisible by every one of its digits.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 999999792 and 999999801.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 2314599 + ... + 2315030.

Almost surely, 2^999999864 is an apocalyptic number.

It is an amenable number.

999999864 is an abundant number, since it is smaller than the sum of its proper divisors (1777778136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

999999864 is a wasteful number, since it uses less digits than its factorization.

999999864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4629644 (or 4629634 counting only the distinct ones).

The product of its digits is 102036672, while the sum is 72.

The square root of 999999864 is about 31622.7744513349. The cubic root of 999999864 is about 999.9999546667. Note that the first 4 decimals are identical.

The spelling of 999999864 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred sixty-four".