81343021 has 2 divisors, whose sum is σ = 81343022. Its totient is φ = 81343020.

The previous prime is 81342991. The next prime is 81343033. The reversal of 81343021 is 12034318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76370121 + 4972900 = 8739^2 + 2230^2 .

It is a cyclic number.

It is not a de Polignac number, because 81343021 - 2⁹ = 81342509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81342983 and 81343001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81343051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40671510 + 40671511.

It is an arithmetic number, because the mean of its divisors is an integer number (40671511).

Almost surely, 2^81343021 is an apocalyptic number.

It is an amenable number.

81343021 is a deficient number, since it is larger than the sum of its proper divisors (1).

81343021 is an equidigital number, since it uses as much as digits as its factorization.

81343021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 81343021 is about 9019.0365893481. The cubic root of 81343021 is about 433.2847787149.

Adding to 81343021 its reverse (12034318), we get a palindrome (93377339).

It can be divided in two parts, 813 and 43021, that added together give a palindrome (43834).

The spelling of 81343021 in words is "eighty-one million, three hundred forty-three thousand, twenty-one".