9906391 has 24 divisors (see below), whose sum is σ = 11916800. Its totient is φ = 8197200.

The previous prime is 9906367. The next prime is 9906401. The reversal of 9906391 is 1936099.

It is not a de Polignac number, because 9906391 - 2⁷ = 9906263 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 9906391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9906361) 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 in 23 ways as a sum of consecutive naturals, for example, 71200 + ... + 71338.

Almost surely, 2^9906391 is an apocalyptic number.

9906391 is a deficient number, since it is larger than the sum of its proper divisors (2010409).

9906391 is a wasteful number, since it uses less digits than its factorization.

9906391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211 (or 200 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 37.

The square root of 9906391 is about 3147.4419772253. The cubic root of 9906391 is about 214.7691121534.

It can be divided in two parts, 990 and 6391, that added together give a triangular number (7381 = T₁₂₁).

The spelling of 9906391 in words is "nine million, nine hundred six thousand, three hundred ninety-one".