51808693 has 4 divisors (see below), whose sum is σ = 51841440. Its totient is φ = 51775948.

The previous prime is 51808643. The next prime is 51808697. The reversal of 51808693 is 39680815.

It is a happy number.

51808693 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is the 2939-th star number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39680815 = 5 ⋅7936163.

It is a cyclic number.

It is not a de Polignac number, because 51808693 - 2¹³ = 51800501 is a prime.

It is a Smith number, since the sum of its digits (40) 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51808697) 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 3 ways as a sum of consecutive naturals, for example, 13873 + ... + 17206.

It is an arithmetic number, because the mean of its divisors is an integer number (12960360).

Almost surely, 2^51808693 is an apocalyptic number.

It is an amenable number.

51808693 is a deficient number, since it is larger than the sum of its proper divisors (32747).

51808693 is a wasteful number, since it uses less digits than its factorization.

51808693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32746.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 51808693 is about 7197.8255744357. The cubic root of 51808693 is about 372.7928253154.

The spelling of 51808693 in words is "fifty-one million, eight hundred eight thousand, six hundred ninety-three".