51721216520761 has 2 divisors, whose sum is σ = 51721216520762. Its totient is φ = 51721216520760.

The previous prime is 51721216520759. The next prime is 51721216520807. The reversal of 51721216520761 is 16702561212715.

It is a happy number.

51721216520761 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (51721216520807) can be obtained adding 51721216520761 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44886730459536 + 6834486061225 = 6699756^2 + 2614285^2 .

It is a cyclic number.

It is not a de Polignac number, because 51721216520761 - 2¹ = 51721216520759 is a prime.

It is a super-3 number, since 3×51721216520761³ (a number of 42 digits) contains 333 as substring.

Together with 51721216520759, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (51721216520731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25860608260380 + 25860608260381.

It is an arithmetic number, because the mean of its divisors is an integer number (25860608260381).

Almost surely, 2^{51721216520761} is an apocalyptic number.

It is an amenable number.

51721216520761 is a deficient number, since it is larger than the sum of its proper divisors (1).

51721216520761 is an equidigital number, since it uses as much as digits as its factorization.

51721216520761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 352800, while the sum is 46.

The spelling of 51721216520761 in words is "fifty-one trillion, seven hundred twenty-one billion, two hundred sixteen million, five hundred twenty thousand, seven hundred sixty-one".