9990905 has 4 divisors (see below), whose sum is σ = 11989092. Its totient is φ = 7992720.

The previous prime is 9990899. The next prime is 9990913. The reversal of 9990905 is 5090999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5090999 = 61 ⋅83459.

It can be written as a sum of positive squares in 2 ways, for example, as 1056784 + 8934121 = 1028^2 + 2989^2 .

It is not a de Polignac number, because 9990905 - 2²² = 5796601 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 999086 + ... + 999095.

It is an arithmetic number, because the mean of its divisors is an integer number (2997273).

Almost surely, 2^9990905 is an apocalyptic number.

It is an amenable number.

9990905 is a deficient number, since it is larger than the sum of its proper divisors (1998187).

9990905 is a wasteful number, since it uses less digits than its factorization.

9990905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1998186.

The product of its (nonzero) digits is 32805, while the sum is 41.

The square root of 9990905 is about 3160.8392872780. The cubic root of 9990905 is about 215.3781339134.

The spelling of 9990905 in words is "nine million, nine hundred ninety thousand, nine hundred five".