81680906 has 16 divisors (see below), whose sum is σ = 125215200. Its totient is φ = 39951120.

The previous prime is 81680899. The next prime is 81680909. The reversal of 81680906 is 60908618.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81680906.

It is not an unprimeable number, because it can be changed into a prime (81680909) 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 in 7 ways as a sum of consecutive naturals, for example, 17921 + ... + 22011.

It is an arithmetic number, because the mean of its divisors is an integer number (7825950).

Almost surely, 2^81680906 is an apocalyptic number.

81680906 is a deficient number, since it is larger than the sum of its proper divisors (43534294).

81680906 is a wasteful number, since it uses less digits than its factorization.

81680906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4309.

The product of its (nonzero) digits is 20736, while the sum is 38.

The square root of 81680906 is about 9037.7489453956. The cubic root of 81680906 is about 433.8838802510.

The spelling of 81680906 in words is "eighty-one million, six hundred eighty thousand, nine hundred six".