51208215581 has 2 divisors, whose sum is σ = 51208215582. Its totient is φ = 51208215580.

The previous prime is 51208215511. The next prime is 51208215659. The reversal of 51208215581 is 18551280215.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34163607556 + 17044608025 = 184834^2 + 130555^2 .

It is a cyclic number.

It is not a de Polignac number, because 51208215581 - 2¹⁰ = 51208214557 is a prime.

It is a super-2 number, since 2×51208215581² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain 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 (51208215511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25604107790 + 25604107791.

It is an arithmetic number, because the mean of its divisors is an integer number (25604107791).

Almost surely, 2^51208215581 is an apocalyptic number.

It is an amenable number.

51208215581 is a deficient number, since it is larger than the sum of its proper divisors (1).

51208215581 is an equidigital number, since it uses as much as digits as its factorization.

51208215581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32000, while the sum is 38.

Adding to 51208215581 its reverse (18551280215), we get a palindrome (69759495796).

The spelling of 51208215581 in words is "fifty-one billion, two hundred eight million, two hundred fifteen thousand, five hundred eighty-one".