51512809 has 4 divisors (see below), whose sum is σ = 51666004. Its totient is φ = 51359616.

The previous prime is 51512803. The next prime is 51512821. The reversal of 51512809 is 90821515.

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 27040000 + 24472809 = 5200^2 + 4947^2 .

It is a cyclic number.

It is not a de Polignac number, because 51512809 - 2¹¹ = 51510761 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51512803) 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, 76092 + ... + 76765.

It is an arithmetic number, because the mean of its divisors is an integer number (12916501).

Almost surely, 2^51512809 is an apocalyptic number.

It is an amenable number.

51512809 is a deficient number, since it is larger than the sum of its proper divisors (153195).

51512809 is a wasteful number, since it uses less digits than its factorization.

51512809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153194.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 51512809 is about 7177.2424370367. The cubic root of 51512809 is about 372.0817857908.

The spelling of 51512809 in words is "fifty-one million, five hundred twelve thousand, eight hundred nine".