71939569781 has 2 divisors, whose sum is σ = 71939569782. Its totient is φ = 71939569780.

The previous prime is 71939569739. The next prime is 71939569829. The reversal of 71939569781 is 18796593917.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66378884881 + 5560684900 = 257641^2 + 74570^2 .

It is an emirp because it is prime and its reverse (18796593917) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71939569781 - 2³⁰ = 70865827957 is a prime.

It is a super-2 number, since 2×71939569781² (a number of 23 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 (71939569081) 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, 35969784890 + 35969784891.

It is an arithmetic number, because the mean of its divisors is an integer number (35969784891).

Almost surely, 2^71939569781 is an apocalyptic number.

It is an amenable number.

71939569781 is a deficient number, since it is larger than the sum of its proper divisors (1).

71939569781 is an equidigital number, since it uses as much as digits as its factorization.

71939569781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25719120, while the sum is 65.

The spelling of 71939569781 in words is "seventy-one billion, nine hundred thirty-nine million, five hundred sixty-nine thousand, seven hundred eighty-one".