81959818 has 8 divisors (see below), whose sum is σ = 122997312. Its totient is φ = 40960716.

The previous prime is 81959803. The next prime is 81959837. The reversal of 81959818 is 81895918.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3480 + ... + 13267.

It is an arithmetic number, because the mean of its divisors is an integer number (15374664).

Almost surely, 2^81959818 is an apocalyptic number.

81959818 is a deficient number, since it is larger than the sum of its proper divisors (41037494).

81959818 is a wasteful number, since it uses less digits than its factorization.

81959818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19196.

The product of its digits is 207360, while the sum is 49.

The square root of 81959818 is about 9053.1661864786. The cubic root of 81959818 is about 434.3771735861.

The spelling of 81959818 in words is "eighty-one million, nine hundred fifty-nine thousand, eight hundred eighteen".