51121365809 has 2 divisors, whose sum is σ = 51121365810. Its totient is φ = 51121365808.

The previous prime is 51121365803. The next prime is 51121365853. The reversal of 51121365809 is 90856312115.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 51100863025 + 20502784 = 226055^2 + 4528^2 .

It is a cyclic number.

It is not a de Polignac number, because 51121365809 - 2¹² = 51121361713 is a prime.

It is a super-2 number, since 2×51121365809² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (51121365803) 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, 25560682904 + 25560682905.

It is an arithmetic number, because the mean of its divisors is an integer number (25560682905).

Almost surely, 2^51121365809 is an apocalyptic number.

It is an amenable number.

51121365809 is a deficient number, since it is larger than the sum of its proper divisors (1).

51121365809 is an equidigital number, since it uses as much as digits as its factorization.

51121365809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64800, while the sum is 41.

The spelling of 51121365809 in words is "fifty-one billion, one hundred twenty-one million, three hundred sixty-five thousand, eight hundred nine".