51909 has 16 divisors (see below), whose sum is σ = 81984. Its totient is φ = 29040.

The previous prime is 51907. The next prime is 51913. The reversal of 51909 is 90915.

It is a happy number.

51909 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 is not a de Polignac number, because 51909 - 2¹ = 51907 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51907) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3987 + ... + 3999.

It is an arithmetic number, because the mean of its divisors is an integer number (5124).

2⁵¹⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

51909 is a deficient number, since it is larger than the sum of its proper divisors (30075).

51909 is a wasteful number, since it uses less digits than its factorization.

51909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49 (or 27 counting only the distinct ones).

The product of its (nonzero) digits is 405, while the sum is 24.

The square root of 51909 is about 227.8354669493. The cubic root of 51909 is about 37.3033258732.

The spelling of 51909 in words is "fifty-one thousand, nine hundred nine".