999999866 has 16 divisors (see below), whose sum is σ = 1581006600. Its totient is φ = 473648448.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999866 is 668999999.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 999887641 + 112225 = 31621^2 + 335^2 .

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 999999793 and 999999802.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 159581 + ... + 165728.

Almost surely, 2^999999866 is an apocalyptic number.

999999866 is a deficient number, since it is larger than the sum of its proper divisors (581006734).

999999866 is a wasteful number, since it uses less digits than its factorization.

999999866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325393.

The product of its digits is 153055008, while the sum is 74.

The square root of 999999866 is about 31622.7744829577. The cubic root of 999999866 is about 999.9999553333. Note that the first 4 decimals are identical.

The spelling of 999999866 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred sixty-six".