81831647 has 2 divisors, whose sum is σ = 81831648. Its totient is φ = 81831646.

The previous prime is 81831637. The next prime is 81831691. The reversal of 81831647 is 74613818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81831647 - 2⁶ = 81831583 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81831647.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81831637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40915823 + 40915824.

It is an arithmetic number, because the mean of its divisors is an integer number (40915824).

Almost surely, 2^81831647 is an apocalyptic number.

81831647 is a deficient number, since it is larger than the sum of its proper divisors (1).

81831647 is an equidigital number, since it uses as much as digits as its factorization.

81831647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 38.

The square root of 81831647 is about 9046.0846226420. The cubic root of 81831647 is about 434.1506251582.

The spelling of 81831647 in words is "eighty-one million, eight hundred thirty-one thousand, six hundred forty-seven".