900099991 has 4 divisors (see below), whose sum is σ = 1028685712. Its totient is φ = 771514272.

The previous prime is 900099983. The next prime is 900100027. The reversal of 900099991 is 199990009.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199990009 = 6581 ⋅30389.

It is a cyclic number.

It is not a de Polignac number, because 900099991 - 2³ = 900099983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (900099971) 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, 64292850 + ... + 64292863.

It is an arithmetic number, because the mean of its divisors is an integer number (257171428).

Almost surely, 2^900099991 is an apocalyptic number.

900099991 is a deficient number, since it is larger than the sum of its proper divisors (128585721).

900099991 is a wasteful number, since it uses less digits than its factorization.

900099991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128585720.

The product of its (nonzero) digits is 59049, while the sum is 46.

The square root of 900099991 is about 30001.6664703813. Note that the first 3 decimals coincide. The cubic root of 900099991 is about 965.5251389293.

It can be divided in two parts, 90009 and 9991, that added together give a 5-th power (100000 = 10⁵).

The spelling of 900099991 in words is "nine hundred million, ninety-nine thousand, nine hundred ninety-one".