51681566539 has 2 divisors, whose sum is σ = 51681566540. Its totient is φ = 51681566538.

The previous prime is 51681566483. The next prime is 51681566557. The reversal of 51681566539 is 93566518615.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51681566539 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51681566539.

It is not a weakly prime, because it can be changed into another prime (51681566039) by changing a digit.

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 as a sum of consecutive naturals, namely, 25840783269 + 25840783270.

It is an arithmetic number, because the mean of its divisors is an integer number (25840783270).

Almost surely, 2^51681566539 is an apocalyptic number.

51681566539 is a deficient number, since it is larger than the sum of its proper divisors (1).

51681566539 is an equidigital number, since it uses as much as digits as its factorization.

51681566539 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832000, while the sum is 55.

The spelling of 51681566539 in words is "fifty-one billion, six hundred eighty-one million, five hundred sixty-six thousand, five hundred thirty-nine".