51624521665 has 4 divisors (see below), whose sum is σ = 61949426004. Its totient is φ = 41299617328.

The previous prime is 51624521647. The next prime is 51624521677. The reversal of 51624521665 is 56612542615.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56612542615 = 5 ⋅11322508523.

It can be written as a sum of positive squares in 2 ways, for example, as 19198596481 + 32425925184 = 138559^2 + 180072^2 .

It is a cyclic number.

It is not a de Polignac number, because 51624521665 - 2⁵ = 51624521633 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5162452162 + ... + 5162452171.

It is an arithmetic number, because the mean of its divisors is an integer number (15487356501).

Almost surely, 2^51624521665 is an apocalyptic number.

It is an amenable number.

51624521665 is a deficient number, since it is larger than the sum of its proper divisors (10324904339).

51624521665 is a wasteful number, since it uses less digits than its factorization.

51624521665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10324904338.

The product of its digits is 432000, while the sum is 43.

The spelling of 51624521665 in words is "fifty-one billion, six hundred twenty-four million, five hundred twenty-one thousand, six hundred sixty-five".