51661651116161 has 2 divisors, whose sum is σ = 51661651116162. Its totient is φ = 51661651116160.

The previous prime is 51661651116139. The next prime is 51661651116169. The reversal of 51661651116161 is 16161115616615.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49691996055025 + 1969655061136 = 7049255^2 + 1403444^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51661651116161 is a prime.

It is not a weakly prime, because it can be changed into another prime (51661651116169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25830825558080 + 25830825558081.

It is an arithmetic number, because the mean of its divisors is an integer number (25830825558081).

Almost surely, 2^{51661651116161} is an apocalyptic number.

It is an amenable number.

51661651116161 is a deficient number, since it is larger than the sum of its proper divisors (1).

51661651116161 is an equidigital number, since it uses as much as digits as its factorization.

51661651116161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 194400, while the sum is 47.

The spelling of 51661651116161 in words is "fifty-one trillion, six hundred sixty-one billion, six hundred fifty-one million, one hundred sixteen thousand, one hundred sixty-one".