81859818 has 16 divisors (see below), whose sum is σ = 164805696. Its totient is φ = 27105600.

The previous prime is 81859801. The next prime is 81859823. The reversal of 81859818 is 81895818.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44271 + ... + 46082.

It is an arithmetic number, because the mean of its divisors is an integer number (10300356).

Almost surely, 2^81859818 is an apocalyptic number.

81859818 is an abundant number, since it is smaller than the sum of its proper divisors (82945878).

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

81859818 is a wasteful number, since it uses less digits than its factorization.

81859818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90509.

The product of its digits is 184320, while the sum is 48.

The square root of 81859818 is about 9047.6415711499. The cubic root of 81859818 is about 434.2004390322.

The spelling of 81859818 in words is "eighty-one million, eight hundred fifty-nine thousand, eight hundred eighteen".