999843521 has 2 divisors, whose sum is σ = 999843522. Its totient is φ = 999843520.

The previous prime is 999843499. The next prime is 999843539. The reversal of 999843521 is 125348999.

It is a happy number.

999843521 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., 779023921 + 220819600 = 27911^2 + 14860^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-999843521 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 999843521.

It is not a weakly prime, because it can be changed into another prime (999843571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499921760 + 499921761.

It is an arithmetic number, because the mean of its divisors is an integer number (499921761).

Almost surely, 2^999843521 is an apocalyptic number.

It is an amenable number.

999843521 is a deficient number, since it is larger than the sum of its proper divisors (1).

999843521 is an equidigital number, since it uses as much as digits as its factorization.

999843521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 50.

The square root of 999843521 is about 31620.3023546582. The cubic root of 999843521 is about 999.9478376125.

The spelling of 999843521 in words is "nine hundred ninety-nine million, eight hundred forty-three thousand, five hundred twenty-one".