51008809 has 4 divisors (see below), whose sum is σ = 51351300. Its totient is φ = 50666320.

The previous prime is 51008807. The next prime is 51008813. The reversal of 51008809 is 90880015.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12531600 + 38477209 = 3540^2 + 6203^2 .

It is a cyclic number.

It is not a de Polignac number, because 51008809 - 2¹ = 51008807 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51008801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 171022 + ... + 171319.

It is an arithmetic number, because the mean of its divisors is an integer number (12837825).

Almost surely, 2^51008809 is an apocalyptic number.

It is an amenable number.

51008809 is a deficient number, since it is larger than the sum of its proper divisors (342491).

51008809 is a wasteful number, since it uses less digits than its factorization.

51008809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 342490.

The product of its (nonzero) digits is 2880, while the sum is 31.

The square root of 51008809 is about 7142.0451552759. The cubic root of 51008809 is about 370.8643270424.

The spelling of 51008809 in words is "fifty-one million, eight thousand, eight hundred nine".