51220720 has 20 divisors (see below), whose sum is σ = 119088360. Its totient is φ = 20488256.

The previous prime is 51220717. The next prime is 51220721. The reversal of 51220720 is 2702215.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51220721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 320050 + ... + 320209.

It is an arithmetic number, because the mean of its divisors is an integer number (5954418).

Almost surely, 2^51220720 is an apocalyptic number.

It is an amenable number.

51220720 is an abundant number, since it is smaller than the sum of its proper divisors (67867640).

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

51220720 is a wasteful number, since it uses less digits than its factorization.

51220720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640272 (or 640266 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 51220720 is about 7156.8652355623. The cubic root of 51220720 is about 371.3771904130.

Adding to 51220720 its reverse (2702215), we get a palindrome (53922935).

The spelling of 51220720 in words is "fifty-one million, two hundred twenty thousand, seven hundred twenty".