51705809 has 2 divisors, whose sum is σ = 51705810. Its totient is φ = 51705808.

The previous prime is 51705791. The next prime is 51705847. The reversal of 51705809 is 90850715.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40043584 + 11662225 = 6328^2 + 3415^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51705809 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (51705209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25852904 + 25852905.

It is an arithmetic number, because the mean of its divisors is an integer number (25852905).

Almost surely, 2^51705809 is an apocalyptic number.

It is an amenable number.

51705809 is a deficient number, since it is larger than the sum of its proper divisors (1).

51705809 is an equidigital number, since it uses as much as digits as its factorization.

51705809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12600, while the sum is 35.

The square root of 51705809 is about 7190.6751421546. The cubic root of 51705809 is about 372.5458922783.

The spelling of 51705809 in words is "fifty-one million, seven hundred five thousand, eight hundred nine".