71213173111981 has 2 divisors, whose sum is σ = 71213173111982. Its totient is φ = 71213173111980.

The previous prime is 71213173111961. The next prime is 71213173112087. The reversal of 71213173111981 is 18911137131217.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69155357040900 + 2057816071081 = 8315970^2 + 1434509^2 .

It is an emirp because it is prime and its reverse (18911137131217) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71213173111981 is a prime.

It is a super-2 number, since 2×71213173111981² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71213173111921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35606586555990 + 35606586555991.

It is an arithmetic number, because the mean of its divisors is an integer number (35606586555991).

Almost surely, 2^{71213173111981} is an apocalyptic number.

It is an amenable number.

71213173111981 is a deficient number, since it is larger than the sum of its proper divisors (1).

71213173111981 is an equidigital number, since it uses as much as digits as its factorization.

71213173111981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63504, while the sum is 46.

The spelling of 71213173111981 in words is "seventy-one trillion, two hundred thirteen billion, one hundred seventy-three million, one hundred eleven thousand, nine hundred eighty-one".