81711556 has 12 divisors (see below), whose sum is σ = 143273340. Its totient is φ = 40776320.

The previous prime is 81711529. The next prime is 81711559. The reversal of 81711556 is 65511718.

It can be written as a sum of positive squares in 2 ways, for example, as 55353600 + 26357956 = 7440^2 + 5134^2 .

It is a super-2 number, since 2×81711556² = 13353556767882272, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81711559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17521 + ... + 21688.

It is an arithmetic number, because the mean of its divisors is an integer number (11939445).

Almost surely, 2^81711556 is an apocalyptic number.

It is an amenable number.

81711556 is a deficient number, since it is larger than the sum of its proper divisors (61561784).

81711556 is a wasteful number, since it uses less digits than its factorization.

81711556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39734 (or 39732 counting only the distinct ones).

The product of its digits is 8400, while the sum is 34.

The square root of 81711556 is about 9039.4444519561. Note that the first 4 decimals coincide. The cubic root of 81711556 is about 433.9381437606.

The spelling of 81711556 in words is "eighty-one million, seven hundred eleven thousand, five hundred fifty-six".