81940039 has 2 divisors, whose sum is σ = 81940040. Its totient is φ = 81940038.

The previous prime is 81940021. The next prime is 81940073. The reversal of 81940039 is 93004918.

It is an a-pointer prime, because the next prime (81940073) can be obtained adding 81940039 to its sum of digits (34).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81940039 - 2¹⁹ = 81415751 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81939986 and 81940013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81940009) 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, 40970019 + 40970020.

It is an arithmetic number, because the mean of its divisors is an integer number (40970020).

Almost surely, 2^81940039 is an apocalyptic number.

81940039 is a deficient number, since it is larger than the sum of its proper divisors (1).

81940039 is an equidigital number, since it uses as much as digits as its factorization.

81940039 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 81940039 is about 9052.0737403095. The cubic root of 81940039 is about 434.3422286682.

The spelling of 81940039 in words is "eighty-one million, nine hundred forty thousand, thirty-nine".