81720588 has 24 divisors (see below), whose sum is σ = 196833280. Its totient is φ = 26361360.

The previous prime is 81720571. The next prime is 81720589. The reversal of 81720588 is 88502718.

It is not an unprimeable number, because it can be changed into a prime (81720589) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 109468 + ... + 110211.

Almost surely, 2^81720588 is an apocalyptic number.

It is an amenable number.

81720588 is an abundant number, since it is smaller than the sum of its proper divisors (115112692).

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

81720588 is a wasteful number, since it uses less digits than its factorization.

81720588 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219717 (or 219715 counting only the distinct ones).

The product of its (nonzero) digits is 35840, while the sum is 39.

The square root of 81720588 is about 9039.9440263754. The cubic root of 81720588 is about 433.9541316458.

The spelling of 81720588 in words is "eighty-one million, seven hundred twenty thousand, five hundred eighty-eight".