81320417 has 2 divisors, whose sum is σ = 81320418. Its totient is φ = 81320416.

The previous prime is 81320377. The next prime is 81320423. The reversal of 81320417 is 71402318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78836641 + 2483776 = 8879^2 + 1576^2 .

It is a cyclic number.

It is not a de Polignac number, because 81320417 - 2¹⁶ = 81254881 is a prime.

It is a super-2 number, since 2×81320417² = 13226020442107778, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81320017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40660208 + 40660209.

It is an arithmetic number, because the mean of its divisors is an integer number (40660209).

Almost surely, 2^81320417 is an apocalyptic number.

It is an amenable number.

81320417 is a deficient number, since it is larger than the sum of its proper divisors (1).

81320417 is an equidigital number, since it uses as much as digits as its factorization.

81320417 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 81320417 is about 9017.7833750873. The cubic root of 81320417 is about 433.2446405594.

The spelling of 81320417 in words is "eighty-one million, three hundred twenty thousand, four hundred seventeen".