999999870 has 16 divisors (see below), whose sum is σ = 2399999760. Its totient is φ = 266666624.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999870 is 78999999.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 999999795 and 999999804.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 16666635 + ... + 16666694.

It is an arithmetic number, because the mean of its divisors is an integer number (149999985).

Almost surely, 2^999999870 is an apocalyptic number.

999999870 is an abundant number, since it is smaller than the sum of its proper divisors (1399999890).

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

999999870 is a wasteful number, since it uses less digits than its factorization.

999999870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33333339.

The product of its (nonzero) digits is 29760696, while the sum is 69.

The square root of 999999870 is about 31622.7745462032. The cubic root of 999999870 is about 999.9999566667. Note that the first 4 decimals are identical.

The spelling of 999999870 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred seventy".