51615550561 has 4 divisors (see below), whose sum is σ = 52097938992. Its totient is φ = 51133162132.

The previous prime is 51615550543. The next prime is 51615550577. The reversal of 51615550561 is 16505551615.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51615550561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51615550531) 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 3 ways as a sum of consecutive naturals, for example, 241194055 + ... + 241194268.

It is an arithmetic number, because the mean of its divisors is an integer number (13024484748).

Almost surely, 2^51615550561 is an apocalyptic number.

It is an amenable number.

51615550561 is a deficient number, since it is larger than the sum of its proper divisors (482388431).

51615550561 is a wasteful number, since it uses less digits than its factorization.

51615550561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482388430.

The product of its (nonzero) digits is 112500, while the sum is 40.

It can be divided in two parts, 51615 and 550561, that added together give a square (602176 = 776²).

The spelling of 51615550561 in words is "fifty-one billion, six hundred fifteen million, five hundred fifty thousand, five hundred sixty-one".