81917916 has 24 divisors (see below), whose sum is σ = 192931200. Its totient is φ = 27050352.

The previous prime is 81917909. The next prime is 81917977. The reversal of 81917916 is 61971918.

It is a congruent number.

It is an unprimeable number.

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, 30616 + ... + 33183.

It is an arithmetic number, because the mean of its divisors is an integer number (8038800).

Almost surely, 2^81917916 is an apocalyptic number.

It is an amenable number.

81917916 is an abundant number, since it is smaller than the sum of its proper divisors (111013284).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81917916 is a wasteful number, since it uses less digits than its factorization.

81917916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63913 (or 63911 counting only the distinct ones).

The product of its digits is 27216, while the sum is 42.

The square root of 81917916 is about 9050.8516726328. The cubic root of 81917916 is about 434.3031357813.

The spelling of 81917916 in words is "eighty-one million, nine hundred seventeen thousand, nine hundred sixteen".