81739513 has 2 divisors, whose sum is σ = 81739514. Its totient is φ = 81739512.

The previous prime is 81739499. The next prime is 81739571. The reversal of 81739513 is 31593718.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41835024 + 39904489 = 6468^2 + 6317^2 .

It is a cyclic number.

It is not a de Polignac number, because 81739513 - 2⁵ = 81739481 is a prime.

It is not a weakly prime, because it can be changed into another prime (81749513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40869756 + 40869757.

It is an arithmetic number, because the mean of its divisors is an integer number (40869757).

Almost surely, 2^81739513 is an apocalyptic number.

It is an amenable number.

81739513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81739513 is an equidigital number, since it uses as much as digits as its factorization.

81739513 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 37.

The square root of 81739513 is about 9040.9907089876. The cubic root of 81739513 is about 433.9876276850.

The spelling of 81739513 in words is "eighty-one million, seven hundred thirty-nine thousand, five hundred thirteen".