999688649 has 2 divisors, whose sum is σ = 999688650. Its totient is φ = 999688648.

The previous prime is 999688643. The next prime is 999688699. The reversal of 999688649 is 946886999.

999688649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 906913225 + 92775424 = 30115^2 + 9632^2 .

It is an emirp because it is prime and its reverse (946886999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999688649 - 2⁴ = 999688633 is a prime.

It is not a weakly prime, because it can be changed into another prime (999688643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499844324 + 499844325.

It is an arithmetic number, because the mean of its divisors is an integer number (499844325).

Almost surely, 2^999688649 is an apocalyptic number.

It is an amenable number.

999688649 is a deficient number, since it is larger than the sum of its proper divisors (1).

999688649 is an equidigital number, since it uses as much as digits as its factorization.

999688649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60466176, while the sum is 68.

The square root of 999688649 is about 31617.8533268785. The cubic root of 999688649 is about 999.8962055604.

The spelling of 999688649 in words is "nine hundred ninety-nine million, six hundred eighty-eight thousand, six hundred forty-nine".