51688509 has 8 divisors (see below), whose sum is σ = 69078912. Its totient is φ = 34378560.

The previous prime is 51688471. The next prime is 51688513. The reversal of 51688509 is 90588615.

51688509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 51688509 - 2⁹ = 51687997 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51688909) 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 in 7 ways as a sum of consecutive naturals, for example, 18597 + ... + 21194.

It is an arithmetic number, because the mean of its divisors is an integer number (8634864).

Almost surely, 2^51688509 is an apocalyptic number.

It is an amenable number.

51688509 is a deficient number, since it is larger than the sum of its proper divisors (17390403).

51688509 is a wasteful number, since it uses less digits than its factorization.

51688509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40227.

The product of its (nonzero) digits is 86400, while the sum is 42.

The square root of 51688509 is about 7189.4720946673. The cubic root of 51688509 is about 372.5043381925.

The spelling of 51688509 in words is "fifty-one million, six hundred eighty-eight thousand, five hundred nine".