51540 has 24 divisors (see below), whose sum is σ = 144480. Its totient is φ = 13728.

The previous prime is 51539. The next prime is 51551. The reversal of 51540 is 4515.

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

It is a nialpdrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 370 + ... + 489.

It is an arithmetic number, because the mean of its divisors is an integer number (6020).

2⁵¹⁵⁴⁰ is an apocalyptic number.

It is an amenable number.

51540 is an abundant number, since it is smaller than the sum of its proper divisors (92940).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72240).

51540 is a wasteful number, since it uses less digits than its factorization.

51540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 871 (or 869 counting only the distinct ones).

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

The square root of 51540 is about 227.0242277820. The cubic root of 51540 is about 37.2147241978.

It can be divided in two parts, 515 and 40, that added together give a palindrome (555).

The spelling of 51540 in words is "fifty-one thousand, five hundred forty".