9906991 has 2 divisors, whose sum is σ = 9906992. Its totient is φ = 9906990.

The previous prime is 9906983. The next prime is 9907003. The reversal of 9906991 is 1996099.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9906991 - 2³ = 9906983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9906931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4953495 + 4953496.

It is an arithmetic number, because the mean of its divisors is an integer number (4953496).

Almost surely, 2^9906991 is an apocalyptic number.

9906991 is a deficient number, since it is larger than the sum of its proper divisors (1).

9906991 is an equidigital number, since it uses as much as digits as its factorization.

9906991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 39366, while the sum is 43.

The square root of 9906991 is about 3147.5372912803. The cubic root of 9906991 is about 214.7734480367.

The spelling of 9906991 in words is "nine million, nine hundred six thousand, nine hundred ninety-one".