991606709 has 2 divisors, whose sum is σ = 991606710. Its totient is φ = 991606708.

The previous prime is 991606663. The next prime is 991606717. The reversal of 991606709 is 907606199.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 858665809 + 132940900 = 29303^2 + 11530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991606709 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991606769) 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 as a sum of consecutive naturals, namely, 495803354 + 495803355.

It is an arithmetic number, because the mean of its divisors is an integer number (495803355).

Almost surely, 2^991606709 is an apocalyptic number.

It is an amenable number.

991606709 is a deficient number, since it is larger than the sum of its proper divisors (1).

991606709 is an equidigital number, since it uses as much as digits as its factorization.

991606709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 183708, while the sum is 47.

The square root of 991606709 is about 31489.7873762272. The cubic root of 991606709 is about 997.1943721472.

The spelling of 991606709 in words is "nine hundred ninety-one million, six hundred six thousand, seven hundred nine".