81443321 has 2 divisors, whose sum is σ = 81443322. Its totient is φ = 81443320.

The previous prime is 81443267. The next prime is 81443347. The reversal of 81443321 is 12334418.

It is an a-pointer prime, because the next prime (81443347) can be obtained adding 81443321 to its sum of digits (26).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79905721 + 1537600 = 8939^2 + 1240^2 .

It is a cyclic number.

It is not a de Polignac number, because 81443321 - 2¹⁰ = 81442297 is a prime.

It is not a weakly prime, because it can be changed into another prime (81440321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40721660 + 40721661.

It is an arithmetic number, because the mean of its divisors is an integer number (40721661).

Almost surely, 2^81443321 is an apocalyptic number.

It is an amenable number.

81443321 is a deficient number, since it is larger than the sum of its proper divisors (1).

81443321 is an equidigital number, since it uses as much as digits as its factorization.

81443321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2304, while the sum is 26.

The square root of 81443321 is about 9024.5953371883. The cubic root of 81443321 is about 433.4627928122.

Adding to 81443321 its reverse (12334418), we get a palindrome (93777739).

The spelling of 81443321 in words is "eighty-one million, four hundred forty-three thousand, three hundred twenty-one".