51215305520 has 20 divisors (see below), whose sum is σ = 119075585520. Its totient is φ = 20486122176.

The previous prime is 51215305511. The next prime is 51215305523. The reversal of 51215305520 is 2550351215.

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

It is not an unprimeable number, because it can be changed into a prime (51215305523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 320095580 + ... + 320095739.

It is an arithmetic number, because the mean of its divisors is an integer number (5953779276).

Almost surely, 2^51215305520 is an apocalyptic number.

It is an amenable number.

51215305520 is an abundant number, since it is smaller than the sum of its proper divisors (67860280000).

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

51215305520 is a wasteful number, since it uses less digits than its factorization.

51215305520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 640191332 (or 640191326 counting only the distinct ones).

The product of its (nonzero) digits is 7500, while the sum is 29.

Adding to 51215305520 its reverse (2550351215), we get a palindrome (53765656735).

The spelling of 51215305520 in words is "fifty-one billion, two hundred fifteen million, three hundred five thousand, five hundred twenty".