51309 has 6 divisors (see below), whose sum is σ = 74126. Its totient is φ = 34200.

The previous prime is 51307. The next prime is 51329. The reversal of 51309 is 90315.

51309 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 49284 + 2025 = 222^2 + 45^2 .

It is not a de Polignac number, because 51309 - 2¹ = 51307 is a prime.

It is a super-2 number, since 2×51309² = 5265226962, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 51291 and 51300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51307) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2842 + ... + 2859.

2⁵¹³⁰⁹ is an apocalyptic number.

It is an amenable number.

51309 is a deficient number, since it is larger than the sum of its proper divisors (22817).

51309 is a wasteful number, since it uses less digits than its factorization.

51309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5707 (or 5704 counting only the distinct ones).

The product of its (nonzero) digits is 135, while the sum is 18.

The square root of 51309 is about 226.5149001722. The cubic root of 51309 is about 37.1590426782.

The spelling of 51309 in words is "fifty-one thousand, three hundred nine".