999991228 has 12 divisors (see below), whose sum is σ = 1752551640. Its totient is φ = 499262192.

The previous prime is 999991207. The next prime is 999991229. The reversal of 999991228 is 822199999.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999991229) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 180283 + ... + 185746.

It is an arithmetic number, because the mean of its divisors is an integer number (146045970).

Almost surely, 2^999991228 is an apocalyptic number.

It is an amenable number.

999991228 is a deficient number, since it is larger than the sum of its proper divisors (752560412).

999991228 is a wasteful number, since it uses less digits than its factorization.

999991228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 366716 (or 366714 counting only the distinct ones).

The product of its digits is 1889568, while the sum is 58.

The square root of 999991228 is about 31622.6379038815. The cubic root of 999991228 is about 999.9970759915.

The spelling of 999991228 in words is "nine hundred ninety-nine million, nine hundred ninety-one thousand, two hundred twenty-eight".