51221656520 has 64 divisors (see below), whose sum is σ = 115911874800. Its totient is φ = 20371087360.

The previous prime is 51221656501. The next prime is 51221656529. The reversal of 51221656520 is 2565612215.

It can be written as a sum of positive squares in 8 ways, for example, as 8836 + 51221647684 = 94^2 + 226322^2 .

It is not an unprimeable number, because it can be changed into a prime (51221656529) 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 15 ways as a sum of consecutive naturals, for example, 5601392 + ... + 5610528.

Almost surely, 2^51221656520 is an apocalyptic number.

It is an amenable number.

51221656520 is an abundant number, since it is smaller than the sum of its proper divisors (64690218280).

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

51221656520 is a wasteful number, since it uses less digits than its factorization.

51221656520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9938 (or 9934 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 35.

The spelling of 51221656520 in words is "fifty-one billion, two hundred twenty-one million, six hundred fifty-six thousand, five hundred twenty".