81680824 has 8 divisors (see below), whose sum is σ = 153151560. Its totient is φ = 40840408.

The previous prime is 81680813. The next prime is 81680827. The reversal of 81680824 is 42808618.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81680827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5105044 + ... + 5105059.

It is an arithmetic number, because the mean of its divisors is an integer number (19143945).

Almost surely, 2^81680824 is an apocalyptic number.

It is an amenable number.

81680824 is a deficient number, since it is larger than the sum of its proper divisors (71470736).

81680824 is a wasteful number, since it uses less digits than its factorization.

81680824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10210109 (or 10210105 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 37.

The square root of 81680824 is about 9037.7444088666. The cubic root of 81680824 is about 433.8837350580.

The spelling of 81680824 in words is "eighty-one million, six hundred eighty thousand, eight hundred twenty-four".