51516606665 has 4 divisors (see below), whose sum is σ = 61819928004. Its totient is φ = 41213285328.

The previous prime is 51516606643. The next prime is 51516606679. The reversal of 51516606665 is 56660661515.

51516606665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56660661515 = 5 ⋅11332132303.

It can be written as a sum of positive squares in 2 ways, for example, as 27887998009 + 23628608656 = 166997^2 + 153716^2 .

It is a cyclic number.

It is not a de Polignac number, because 51516606665 - 2⁸ = 51516606409 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5151660662 + ... + 5151660671.

It is an arithmetic number, because the mean of its divisors is an integer number (15454982001).

Almost surely, 2^51516606665 is an apocalyptic number.

It is an amenable number.

51516606665 is a deficient number, since it is larger than the sum of its proper divisors (10303321339).

51516606665 is a wasteful number, since it uses less digits than its factorization.

51516606665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10303321338.

The product of its (nonzero) digits is 972000, while the sum is 47.

The spelling of 51516606665 in words is "fifty-one billion, five hundred sixteen million, six hundred six thousand, six hundred sixty-five".