51211720 has 32 divisors (see below), whose sum is σ = 131688000. Its totient is φ = 17558208.

The previous prime is 51211697. The next prime is 51211723. The reversal of 51211720 is 2711215.

51211720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (51211723) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 91170 + ... + 91729.

It is an arithmetic number, because the mean of its divisors is an integer number (4115250).

Almost surely, 2^51211720 is an apocalyptic number.

It is an amenable number.

51211720 is an abundant number, since it is smaller than the sum of its proper divisors (80476280).

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

51211720 is a wasteful number, since it uses less digits than its factorization.

51211720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182917 (or 182913 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 51211720 is about 7156.2364410352. The cubic root of 51211720 is about 371.3554375593.

Adding to 51211720 its reverse (2711215), we get a palindrome (53922935).

The spelling of 51211720 in words is "fifty-one million, two hundred eleven thousand, seven hundred twenty".