81805967 has 2 divisors, whose sum is σ = 81805968. Its totient is φ = 81805966.

The previous prime is 81805943. The next prime is 81805973. The reversal of 81805967 is 76950818.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81805967 - 2⁶ = 81805903 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81805937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40902983 + 40902984.

It is an arithmetic number, because the mean of its divisors is an integer number (40902984).

Almost surely, 2^81805967 is an apocalyptic number.

81805967 is a deficient number, since it is larger than the sum of its proper divisors (1).

81805967 is an equidigital number, since it uses as much as digits as its factorization.

81805967 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 44.

The square root of 81805967 is about 9044.6651126507. The cubic root of 81805967 is about 434.1052060776.

The spelling of 81805967 in words is "eighty-one million, eight hundred five thousand, nine hundred sixty-seven".