81911667 has 8 divisors (see below), whose sum is σ = 109385424. Its totient is φ = 54522848.

The previous prime is 81911633. The next prime is 81911681. The reversal of 81911667 is 76611918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81911667 - 2⁷ = 81911539 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81911617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18948 + ... + 22865.

It is an arithmetic number, because the mean of its divisors is an integer number (13673178).

Almost surely, 2^81911667 is an apocalyptic number.

81911667 is a deficient number, since it is larger than the sum of its proper divisors (27473757).

81911667 is a wasteful number, since it uses less digits than its factorization.

81911667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42469.

The product of its digits is 18144, while the sum is 39.

The square root of 81911667 is about 9050.5064499176. The cubic root of 81911667 is about 434.2920920868.

The spelling of 81911667 in words is "eighty-one million, nine hundred eleven thousand, six hundred sixty-seven".