81805964 has 18 divisors (see below), whose sum is σ = 147144060. Its totient is φ = 39794832.

The previous prime is 81805943. The next prime is 81805967. The reversal of 81805964 is 46950818.

It is not an unprimeable number, because it can be changed into a prime (81805967) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1994 + ... + 12945.

It is an arithmetic number, because the mean of its divisors is an integer number (8174670).

Almost surely, 2^81805964 is an apocalyptic number.

It is an amenable number.

81805964 is a deficient number, since it is larger than the sum of its proper divisors (65338096).

81805964 is a wasteful number, since it uses less digits than its factorization.

81805964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15017 (or 14978 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 41.

The square root of 81805964 is about 9044.6649468070. The cubic root of 81805964 is about 434.1052007711.

The spelling of 81805964 in words is "eighty-one million, eight hundred five thousand, nine hundred sixty-four".