999128881 has 9 divisors (see below), whose sum is σ = 1015347969. Its totient is φ = 983166336.

The previous prime is 999128873. The next prime is 999128903. The reversal of 999128881 is 188821999.

The square root of 999128881 is 31609.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 134768881 + 864360000 = 11609^2 + 29400^2 .

It is not a de Polignac number, because 999128881 - 2³ = 999128873 is a prime.

It is a super-2 number, since 2×999128881² = 1996517041696624322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (999128861) 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 8 ways as a sum of consecutive naturals, for example, 2307241 + ... + 2307673.

It is an arithmetic number, because the mean of its divisors is an integer number (112816441).

Almost surely, 2^999128881 is an apocalyptic number.

999128881 is the 31609-th square number.

999128881 is the 15805-th centered octagonal number.

It is an amenable number.

999128881 is a deficient number, since it is larger than the sum of its proper divisors (16219088).

999128881 is an frugal number, since it uses more digits than its factorization.

999128881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012 (or 506 counting only the distinct ones).

The product of its digits is 746496, while the sum is 55.

The cubic root of 999128881 is about 999.7095426427.

Multiplying 999128881 by its product of digits (746496), we get a square (745845713150976 = 27310176²).

The spelling of 999128881 in words is "nine hundred ninety-nine million, one hundred twenty-eight thousand, eight hundred eighty-one".