81771867 has 6 divisors (see below), whose sum is σ = 118114932. Its totient is φ = 54514572.

The previous prime is 81771821. The next prime is 81771881. The reversal of 81771867 is 76817718.

It is a happy number.

It is not a de Polignac number, because 81771867 - 2¹⁴ = 81755483 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81771167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4542873 + ... + 4542890.

It is an arithmetic number, because the mean of its divisors is an integer number (19685822).

Almost surely, 2^81771867 is an apocalyptic number.

81771867 is a deficient number, since it is larger than the sum of its proper divisors (36343065).

81771867 is a wasteful number, since it uses less digits than its factorization.

81771867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9085769 (or 9085766 counting only the distinct ones).

The product of its digits is 131712, while the sum is 45.

The square root of 81771867 is about 9042.7798270222. The cubic root of 81771867 is about 434.0448802222.

The spelling of 81771867 in words is "eighty-one million, seven hundred seventy-one thousand, eight hundred sixty-seven".