9999866 has 4 divisors (see below), whose sum is σ = 14999802. Its totient is φ = 4999932.

The previous prime is 9999863. The next prime is 9999877. The reversal of 9999866 is 6689999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 7980625 + 2019241 = 2825^2 + 1421^2 .

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (9999863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2499965 + ... + 2499968.

Almost surely, 2^9999866 is an apocalyptic number.

9999866 is a deficient number, since it is larger than the sum of its proper divisors (4999936).

9999866 is a wasteful number, since it uses less digits than its factorization.

9999866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4999935.

The product of its digits is 1889568, while the sum is 56.

The square root of 9999866 is about 3162.2564728371. The cubic root of 9999866 is about 215.4425066847.

The spelling of 9999866 in words is "nine million, nine hundred ninety-nine thousand, eight hundred sixty-six".