71057047781 has 2 divisors, whose sum is σ = 71057047782. Its totient is φ = 71057047780.

The previous prime is 71057047753. The next prime is 71057047793. The reversal of 71057047781 is 18774075017.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59434051681 + 11622996100 = 243791^2 + 107810^2 .

It is an emirp because it is prime and its reverse (18774075017) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71057047781 - 2¹⁰ = 71057046757 is a prime.

It is a super-2 number, since 2×71057047781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71057047681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35528523890 + 35528523891.

It is an arithmetic number, because the mean of its divisors is an integer number (35528523891).

Almost surely, 2^71057047781 is an apocalyptic number.

It is an amenable number.

71057047781 is a deficient number, since it is larger than the sum of its proper divisors (1).

71057047781 is an equidigital number, since it uses as much as digits as its factorization.

71057047781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384160, while the sum is 47.

The spelling of 71057047781 in words is "seventy-one billion, fifty-seven million, forty-seven thousand, seven hundred eighty-one".