81989806 has 16 divisors (see below), whose sum is σ = 125411328. Its totient is φ = 40192600.

The previous prime is 81989801. The next prime is 81989821. The reversal of 81989806 is 60898918.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81989806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81989801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25611 + ... + 28633.

It is an arithmetic number, because the mean of its divisors is an integer number (7838208).

Almost surely, 2^81989806 is an apocalyptic number.

81989806 is a deficient number, since it is larger than the sum of its proper divisors (43421522).

81989806 is a wasteful number, since it uses less digits than its factorization.

81989806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3287.

The product of its (nonzero) digits is 248832, while the sum is 49.

The square root of 81989806 is about 9054.8222511544. The cubic root of 81989806 is about 434.4301447234.

The spelling of 81989806 in words is "eighty-one million, nine hundred eighty-nine thousand, eight hundred six".