81439493 has 2 divisors, whose sum is σ = 81439494. Its totient is φ = 81439492.

The previous prime is 81439483. The next prime is 81439507. The reversal of 81439493 is 39493418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81414529 + 24964 = 9023^2 + 158^2 .

It is a cyclic number.

It is not a de Polignac number, because 81439493 - 2¹² = 81435397 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81439493.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81439403) 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, 40719746 + 40719747.

It is an arithmetic number, because the mean of its divisors is an integer number (40719747).

Almost surely, 2^81439493 is an apocalyptic number.

It is an amenable number.

81439493 is a deficient number, since it is larger than the sum of its proper divisors (1).

81439493 is an equidigital number, since it uses as much as digits as its factorization.

81439493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 41.

The square root of 81439493 is about 9024.3832476242. The cubic root of 81439493 is about 433.4560014979.

The spelling of 81439493 in words is "eighty-one million, four hundred thirty-nine thousand, four hundred ninety-three".