51609 has 4 divisors (see below), whose sum is σ = 68816. Its totient is φ = 34404.

The previous prime is 51607. The next prime is 51613. The reversal of 51609 is 90615.

51609 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 51609 - 2¹ = 51607 is a prime.

It is an Ulam number.

It is a D-number.

It is a Duffinian number.

51609 is a lucky number.

It is a nialpdrome in base 16.

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, 8599 + ... + 8604.

It is an arithmetic number, because the mean of its divisors is an integer number (17204).

2⁵¹⁶⁰⁹ is an apocalyptic number.

It is an amenable number.

51609 is a deficient number, since it is larger than the sum of its proper divisors (17207).

51609 is a wasteful number, since it uses less digits than its factorization.

51609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17206.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 51609 is about 227.1761431137. The cubic root of 51609 is about 37.2313240615.

The spelling of 51609 in words is "fifty-one thousand, six hundred nine".