999999861 has 16 divisors (see below), whose sum is σ = 1526505600. Its totient is φ = 570417408.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999861 is 168999999.

It is not a de Polignac number, because 999999861 - 2⁶ = 999999797 is a prime.

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 (999999761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29896 + ... + 53793.

It is an arithmetic number, because the mean of its divisors is an integer number (95406600).

Almost surely, 2^999999861 is an apocalyptic number.

It is an amenable number.

999999861 is a deficient number, since it is larger than the sum of its proper divisors (526505739).

999999861 is a wasteful number, since it uses less digits than its factorization.

999999861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84268.

The product of its digits is 25509168, while the sum is 69.

The square root of 999999861 is about 31622.7744039007. The cubic root of 999999861 is about 999.9999536667. Note that the first 4 decimals are identical.

The spelling of 999999861 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred sixty-one".