51505555721 has 8 divisors (see below), whose sum is σ = 51606702624. Its totient is φ = 51404474880.

The previous prime is 51505555681. The next prime is 51505555733. The reversal of 51505555721 is 12755550515.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51505555721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (51505555781) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1720346 + ... + 1750028.

It is an arithmetic number, because the mean of its divisors is an integer number (6450837828).

Almost surely, 2^51505555721 is an apocalyptic number.

It is an amenable number.

51505555721 is a deficient number, since it is larger than the sum of its proper divisors (101146903).

51505555721 is a wasteful number, since it uses less digits than its factorization.

51505555721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33031.

The product of its (nonzero) digits is 218750, while the sum is 41.

The spelling of 51505555721 in words is "fifty-one billion, five hundred five million, five hundred fifty-five thousand, seven hundred twenty-one".