51405 has 16 divisors (see below), whose sum is σ = 86400. Its totient is φ = 26048.

The previous prime is 51383. The next prime is 51407. The reversal of 51405 is 50415.

51405 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 51405 - 2⁶ = 51341 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 51405.

It is not an unprimeable number, because it can be changed into a prime (51407) 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, 271 + ... + 419.

It is an arithmetic number, because the mean of its divisors is an integer number (5400).

2⁵¹⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

51405 is a deficient number, since it is larger than the sum of its proper divisors (34995).

51405 is a wasteful number, since it uses less digits than its factorization.

51405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180.

The product of its (nonzero) digits is 100, while the sum is 15.

The square root of 51405 is about 226.7267077342. The cubic root of 51405 is about 37.1822033037.

Subtracting from 51405 its reverse (50415), we obtain a triangular number (990 = T₄₄).

The spelling of 51405 in words is "fifty-one thousand, four hundred five".