51720 has 32 divisors (see below), whose sum is σ = 155520. Its totient is φ = 13760.

The previous prime is 51719. The next prime is 51721. The reversal of 51720 is 2715.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (51719) and next prime (51721).

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

It is a self number, because there is not a number n which added to its sum of digits gives 51720.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 96 + ... + 335.

It is an arithmetic number, because the mean of its divisors is an integer number (4860).

2⁵¹⁷²⁰ is an apocalyptic number.

It is an amenable number.

51720 is an abundant number, since it is smaller than the sum of its proper divisors (103800).

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 (77760).

51720 is a wasteful number, since it uses less digits than its factorization.

51720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445 (or 441 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 15.

The square root of 51720 is about 227.4203157152. The cubic root of 51720 is about 37.2579971719.

The spelling of 51720 in words is "fifty-one thousand, seven hundred twenty".