51213220 has 12 divisors (see below), whose sum is σ = 107547804. Its totient is φ = 20485280.

The previous prime is 51213199. The next prime is 51213233. The reversal of 51213220 is 2231215.

51213220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 11573604 + 39639616 = 3402^2 + 6296^2 .

It is a junction number, because it is equal to n+sod(n) for n = 51213194 and 51213203.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1280311 + ... + 1280350.

It is an arithmetic number, because the mean of its divisors is an integer number (8962317).

Almost surely, 2^51213220 is an apocalyptic number.

It is an amenable number.

51213220 is an abundant number, since it is smaller than the sum of its proper divisors (56334584).

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

51213220 is a wasteful number, since it uses less digits than its factorization.

51213220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2560670 (or 2560668 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 51213220 is about 7156.3412439598. The cubic root of 51213220 is about 371.3590632119.

Adding to 51213220 its reverse (2231215), we get a palindrome (53444435).

The spelling of 51213220 in words is "fifty-one million, two hundred thirteen thousand, two hundred twenty".