51220 has 24 divisors (see below), whose sum is σ = 116424. Its totient is φ = 18816.

The previous prime is 51217. The next prime is 51229. The reversal of 51220 is 2215.

It can be written as a sum of positive squares in 4 ways, for example, as 9604 + 41616 = 98^2 + 204^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 51197 and 51206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51229) 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, 162 + ... + 358.

It is an arithmetic number, because the mean of its divisors is an integer number (4851).

2⁵¹²²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 51220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (58212).

51220 is an abundant number, since it is smaller than the sum of its proper divisors (65204).

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

51220 is a wasteful number, since it uses less digits than its factorization.

51220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 10.

The square root of 51220 is about 226.3183598385. The cubic root of 51220 is about 37.1375450279.

Adding to 51220 its reverse (2215), we get a palindrome (53435).

It can be divided in two parts, 5 and 1220, that added together give a triangular number (1225 = T₄₉).

The spelling of 51220 in words is "fifty-one thousand, two hundred twenty".