71838721 has 2 divisors, whose sum is σ = 71838722. Its totient is φ = 71838720.

The previous prime is 71838707. The next prime is 71838731. The reversal of 71838721 is 12783817.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69555600 + 2283121 = 8340^2 + 1511^2 .

It is an emirp because it is prime and its reverse (12783817) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71838721 - 2⁷ = 71838593 is a prime.

It is not a weakly prime, because it can be changed into another prime (71838731) 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, 35919360 + 35919361.

It is an arithmetic number, because the mean of its divisors is an integer number (35919361).

Almost surely, 2^71838721 is an apocalyptic number.

It is an amenable number.

71838721 is a deficient number, since it is larger than the sum of its proper divisors (1).

71838721 is an equidigital number, since it uses as much as digits as its factorization.

71838721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18816, while the sum is 37.

The square root of 71838721 is about 8475.7725901537. The cubic root of 71838721 is about 415.7059084653.

The spelling of 71838721 in words is "seventy-one million, eight hundred thirty-eight thousand, seven hundred twenty-one".