81585656 has 32 divisors (see below), whose sum is σ = 156608640. Its totient is φ = 39831168.

The previous prime is 81585653. The next prime is 81585667. The reversal of 81585656 is 65658518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81585653) 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, 134105 + ... + 134711.

It is an arithmetic number, because the mean of its divisors is an integer number (4894020).

Almost surely, 2^81585656 is an apocalyptic number.

It is an amenable number.

81585656 is a deficient number, since it is larger than the sum of its proper divisors (75022984).

81585656 is a wasteful number, since it uses less digits than its factorization.

81585656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 983 (or 979 counting only the distinct ones).

The product of its digits is 288000, while the sum is 44.

The square root of 81585656 is about 9032.4778438699. The cubic root of 81585656 is about 433.7151606308.

The spelling of 81585656 in words is "eighty-one million, five hundred eighty-five thousand, six hundred fifty-six".