51491066543509 has 2 divisors, whose sum is σ = 51491066543510. Its totient is φ = 51491066543508.

The previous prime is 51491066543407. The next prime is 51491066543531. The reversal of 51491066543509 is 90534566019415.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31358768012100 + 20132298531409 = 5599890^2 + 4486903^2 .

It is a cyclic number.

It is not a de Polignac number, because 51491066543509 - 2²¹ = 51491064446357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51491066544509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25745533271754 + 25745533271755.

It is an arithmetic number, because the mean of its divisors is an integer number (25745533271755).

Almost surely, 2^{51491066543509} is an apocalyptic number.

It is an amenable number.

51491066543509 is a deficient number, since it is larger than the sum of its proper divisors (1).

51491066543509 is an equidigital number, since it uses as much as digits as its factorization.

51491066543509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17496000, while the sum is 58.

The spelling of 51491066543509 in words is "fifty-one trillion, four hundred ninety-one billion, sixty-six million, five hundred forty-three thousand, five hundred nine".