999999872 has 16 divisors (see below), whose sum is σ = 1992187500. Its totient is φ = 499999872.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999872 is 278999999.

It is a tau number, because it is divible by the number of its divisors (16).

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 999999796 and 999999805.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3906122 + ... + 3906377.

Almost surely, 2^999999872 is an apocalyptic number.

It is an amenable number.

999999872 is a deficient number, since it is larger than the sum of its proper divisors (992187628).

999999872 is an equidigital number, since it uses as much as digits as its factorization.

999999872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7812513 (or 7812501 counting only the distinct ones).

The product of its digits is 59521392, while the sum is 71.

The square root of 999999872 is about 31622.7745778260. The cubic root of 999999872 is about 999.9999573333. Note that the first 4 decimals are identical.

The spelling of 999999872 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred seventy-two".