81221983 has 2 divisors, whose sum is σ = 81221984. Its totient is φ = 81221982.

The previous prime is 81221963. The next prime is 81222007. The reversal of 81221983 is 38912218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81221983 - 2⁵ = 81221951 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81221963) 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, 40610991 + 40610992.

It is an arithmetic number, because the mean of its divisors is an integer number (40610992).

Almost surely, 2^81221983 is an apocalyptic number.

81221983 is a deficient number, since it is larger than the sum of its proper divisors (1).

81221983 is an equidigital number, since it uses as much as digits as its factorization.

81221983 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 34.

The square root of 81221983 is about 9012.3239511238. The cubic root of 81221983 is about 433.0697635194.

The spelling of 81221983 in words is "eighty-one million, two hundred twenty-one thousand, nine hundred eighty-three".