81720084 has 24 divisors (see below), whose sum is σ = 191147040. Its totient is φ = 27173344.

The previous prime is 81720047. The next prime is 81720103. The reversal of 81720084 is 48002718.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3099 + ... + 13154.

It is an arithmetic number, because the mean of its divisors is an integer number (7964460).

Almost surely, 2^81720084 is an apocalyptic number.

It is an amenable number.

81720084 is an abundant number, since it is smaller than the sum of its proper divisors (109426956).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81720084 is a wasteful number, since it uses less digits than its factorization.

81720084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16679 (or 16677 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 81720084 is about 9039.9161500536. The cubic root of 81720084 is about 433.9532395273.

The spelling of 81720084 in words is "eighty-one million, seven hundred twenty thousand, eighty-four".