81718580 has 24 divisors (see below), whose sum is σ = 174849192. Its totient is φ = 32070272.

The previous prime is 81718577. The next prime is 81718649. The reversal of 81718580 is 8581718.

It can be written as a sum of positive squares in 4 ways, for example, as 6584356 + 75134224 = 2566^2 + 8668^2 .

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, 37487 + ... + 39606.

It is an arithmetic number, because the mean of its divisors is an integer number (7285383).

Almost surely, 2^81718580 is an apocalyptic number.

It is an amenable number.

81718580 is an abundant number, since it is smaller than the sum of its proper divisors (93130612).

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

81718580 is a wasteful number, since it uses less digits than its factorization.

81718580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77155 (or 77153 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 38.

The square root of 81718580 is about 9039.8329630586. The cubic root of 81718580 is about 433.9505773108.

The spelling of 81718580 in words is "eighty-one million, seven hundred eighteen thousand, five hundred eighty".