81865783 has 2 divisors, whose sum is σ = 81865784. Its totient is φ = 81865782.

The previous prime is 81865747. The next prime is 81865787. The reversal of 81865783 is 38756818.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81865783 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81865787) 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, 40932891 + 40932892.

It is an arithmetic number, because the mean of its divisors is an integer number (40932892).

Almost surely, 2^81865783 is an apocalyptic number.

81865783 is a deficient number, since it is larger than the sum of its proper divisors (1).

81865783 is an equidigital number, since it uses as much as digits as its factorization.

81865783 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 322560, while the sum is 46.

The square root of 81865783 is about 9047.9712090612. The cubic root of 81865783 is about 434.2109852838.

The spelling of 81865783 in words is "eighty-one million, eight hundred sixty-five thousand, seven hundred eighty-three".