51820009 has 2 divisors, whose sum is σ = 51820010. Its totient is φ = 51820008.

The previous prime is 51820007. The next prime is 51820037. The reversal of 51820009 is 90002815.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51768025 + 51984 = 7195^2 + 228^2 .

It is a cyclic number.

It is not a de Polignac number, because 51820009 - 2¹ = 51820007 is a prime.

Together with 51820007, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (51820001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25910004 + 25910005.

It is an arithmetic number, because the mean of its divisors is an integer number (25910005).

Almost surely, 2^51820009 is an apocalyptic number.

It is an amenable number.

51820009 is a deficient number, since it is larger than the sum of its proper divisors (1).

51820009 is an equidigital number, since it uses as much as digits as its factorization.

51820009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 51820009 is about 7198.6116022466. The cubic root of 51820009 is about 372.8199650112.

The spelling of 51820009 in words is "fifty-one million, eight hundred twenty thousand, nine".