51556608821 has 2 divisors, whose sum is σ = 51556608822. Its totient is φ = 51556608820.

The previous prime is 51556608811. The next prime is 51556608823. The reversal of 51556608821 is 12880665515.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 36202672900 + 15353935921 = 190270^2 + 123911^2 .

It is a cyclic number.

It is not a de Polignac number, because 51556608821 - 2⁶ = 51556608757 is a prime.

It is a Sophie Germain prime.

Together with 51556608823, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51556608823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25778304410 + 25778304411.

It is an arithmetic number, because the mean of its divisors is an integer number (25778304411).

Almost surely, 2^51556608821 is an apocalyptic number.

It is an amenable number.

51556608821 is a deficient number, since it is larger than the sum of its proper divisors (1).

51556608821 is an equidigital number, since it uses as much as digits as its factorization.

51556608821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576000, while the sum is 47.

The spelling of 51556608821 in words is "fifty-one billion, five hundred fifty-six million, six hundred eight thousand, eight hundred twenty-one".