9991649 has 2 divisors, whose sum is σ = 9991650. Its totient is φ = 9991648.

The previous prime is 9991603. The next prime is 9991669. The reversal of 9991649 is 9461999.

9991649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6091024 + 3900625 = 2468^2 + 1975^2 .

It is a cyclic number.

It is not a de Polignac number, because 9991649 - 2¹² = 9987553 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (9991669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995824 + 4995825.

It is an arithmetic number, because the mean of its divisors is an integer number (4995825).

Almost surely, 2^9991649 is an apocalyptic number.

It is an amenable number.

9991649 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991649 is an equidigital number, since it uses as much as digits as its factorization.

9991649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 157464, while the sum is 47.

The square root of 9991649 is about 3160.9569753478. The cubic root of 9991649 is about 215.3834800208.

The spelling of 9991649 in words is "nine million, nine hundred ninety-one thousand, six hundred forty-nine".