81655871 has 4 divisors (see below), whose sum is σ = 89079144. Its totient is φ = 74232600.

The previous prime is 81655859. The next prime is 81655883. The reversal of 81655871 is 17855618.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (81655859) and next prime (81655883).

It is a cyclic number.

It is not a de Polignac number, because 81655871 - 2⁶ = 81655807 is a prime.

It is a super-3 number, since 3×81655871³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81655841) 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, 3711620 + ... + 3711641.

It is an arithmetic number, because the mean of its divisors is an integer number (22269786).

Almost surely, 2^81655871 is an apocalyptic number.

81655871 is a deficient number, since it is larger than the sum of its proper divisors (7423273).

81655871 is a wasteful number, since it uses less digits than its factorization.

81655871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7423272.

The product of its digits is 67200, while the sum is 41.

The square root of 81655871 is about 9036.3638151637. The cubic root of 81655871 is about 433.8395476017.

The spelling of 81655871 in words is "eighty-one million, six hundred fifty-five thousand, eight hundred seventy-one".