51605 has 4 divisors (see below), whose sum is σ = 61932. Its totient is φ = 41280.

The previous prime is 51599. The next prime is 51607. The reversal of 51605 is 50615.

51605 is nontrivially palindromic in base 14.

51605 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 23716 + 27889 = 154^2 + 167^2 .

It is not a de Polignac number, because 51605 - 2⁸ = 51349 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5156 + ... + 5165.

It is an arithmetic number, because the mean of its divisors is an integer number (15483).

2⁵¹⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

51605 is a deficient number, since it is larger than the sum of its proper divisors (10327).

51605 is a wasteful number, since it uses less digits than its factorization.

51605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10326.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 51605 is about 227.1673392017. The cubic root of 51605 is about 37.2303621547.

Subtracting from 51605 its reverse (50615), we obtain a triangular number (990 = T₄₄).

It can be divided in two parts, 51 and 605, that added together give a palindrome (656).

The spelling of 51605 in words is "fifty-one thousand, six hundred five".