71320721 has 2 divisors, whose sum is σ = 71320722. Its totient is φ = 71320720.

The previous prime is 71320709. The next prime is 71320727. The reversal of 71320721 is 12702317.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38887696 + 32433025 = 6236^2 + 5695^2 .

It is a cyclic number.

It is not a de Polignac number, because 71320721 - 2¹⁸ = 71058577 is a prime.

It is not a weakly prime, because it can be changed into another prime (71320727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35660360 + 35660361.

It is an arithmetic number, because the mean of its divisors is an integer number (35660361).

Almost surely, 2^71320721 is an apocalyptic number.

It is an amenable number.

71320721 is a deficient number, since it is larger than the sum of its proper divisors (1).

71320721 is an equidigital number, since it uses as much as digits as its factorization.

71320721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 71320721 is about 8445.1596195691. The cubic root of 71320721 is about 414.7043348150.

The spelling of 71320721 in words is "seventy-one million, three hundred twenty thousand, seven hundred twenty-one".