51015561666561 has 6 divisors (see below), whose sum is σ = 73689144629490. Its totient is φ = 34010374444368.

The previous prime is 51015561666523. The next prime is 51015561666569. The reversal of 51015561666561 is 16566616551015.

It can be written as a sum of positive squares in only one way, i.e., 33914491668225 + 17101069998336 = 5823615^2 + 4135344^2 .

It is not a de Polignac number, because 51015561666561 - 2¹¹ = 51015561664513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 51015561666498 and 51015561666507.

It is not an unprimeable number, because it can be changed into a prime (51015561666569) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2834197870356 + ... + 2834197870373.

It is an arithmetic number, because the mean of its divisors is an integer number (12281524104915).

Almost surely, 2^{51015561666561} is an apocalyptic number.

It is an amenable number.

51015561666561 is a deficient number, since it is larger than the sum of its proper divisors (22673582962929).

51015561666561 is a wasteful number, since it uses less digits than its factorization.

51015561666561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5668395740735 (or 5668395740732 counting only the distinct ones).

The product of its (nonzero) digits is 4860000, while the sum is 54.

The spelling of 51015561666561 in words is "fifty-one trillion, fifteen billion, five hundred sixty-one million, six hundred sixty-six thousand, five hundred sixty-one".