81071239 has 2 divisors, whose sum is σ = 81071240. Its totient is φ = 81071238.

The previous prime is 81071219. The next prime is 81071281. The reversal of 81071239 is 93217018.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81071239 - 2¹⁵ = 81038471 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81071239.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81071209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40535619 + 40535620.

It is an arithmetic number, because the mean of its divisors is an integer number (40535620).

Almost surely, 2^81071239 is an apocalyptic number.

81071239 is a deficient number, since it is larger than the sum of its proper divisors (1).

81071239 is an equidigital number, since it uses as much as digits as its factorization.

81071239 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 81071239 is about 9003.9568524066. The cubic root of 81071239 is about 432.8016788834.

The spelling of 81071239 in words is "eighty-one million, seventy-one thousand, two hundred thirty-nine".