249840809 has 2 divisors, whose sum is σ = 249840810. Its totient is φ = 249840808.

The previous prime is 249840769. The next prime is 249840841. The reversal of 249840809 is 908048942.

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., 132595225 + 117245584 = 11515^2 + 10828^2 .

It is a cyclic number.

It is not a de Polignac number, because 249840809 - 2²⁰ = 248792233 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 249840809.

It is not a weakly prime, because it can be changed into another prime (249840859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124920404 + 124920405.

It is an arithmetic number, because the mean of its divisors is an integer number (124920405).

Almost surely, 2^249840809 is an apocalyptic number.

It is an amenable number.

249840809 is a deficient number, since it is larger than the sum of its proper divisors (1).

249840809 is an equidigital number, since it uses as much as digits as its factorization.

249840809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 165888, while the sum is 44.

The square root of 249840809 is about 15806.3534377794. The cubic root of 249840809 is about 629.8267844951.

The spelling of 249840809 in words is "two hundred forty-nine million, eight hundred forty thousand, eight hundred nine".