81708520 has 32 divisors (see below), whose sum is σ = 186066720. Its totient is φ = 32288320.

The previous prime is 81708491. The next prime is 81708521. The reversal of 81708520 is 2580718.

It is not an unprimeable number, because it can be changed into a prime (81708521) 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, 8986 + ... + 15625.

It is an arithmetic number, because the mean of its divisors is an integer number (5814585).

Almost surely, 2^81708520 is an apocalyptic number.

It is an amenable number.

81708520 is an abundant number, since it is smaller than the sum of its proper divisors (104358200).

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

81708520 is a wasteful number, since it uses less digits than its factorization.

81708520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24705 (or 24701 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 81708520 is about 9039.2765197221. The cubic root of 81708520 is about 433.9327693575.

It can be divided in two parts, 81708 and 520, that added together give a palindrome (82228).

The spelling of 81708520 in words is "eighty-one million, seven hundred eight thousand, five hundred twenty".