81947136 has 80 divisors (see below), whose sum is σ = 225485568. Its totient is φ = 26419200.

The previous prime is 81947113. The next prime is 81947141. The reversal of 81947136 is 63174918.

It is a junction number, because it is equal to n+sod(n) for n = 81947094 and 81947103.

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, 46756 + ... + 48476.

Almost surely, 2^81947136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81947136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112742784).

81947136 is an abundant number, since it is smaller than the sum of its proper divisors (143538432).

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

81947136 is a wasteful number, since it uses less digits than its factorization.

81947136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773 (or 1757 counting only the distinct ones).

The product of its digits is 36288, while the sum is 39.

The square root of 81947136 is about 9052.4657414430. The cubic root of 81947136 is about 434.3547680724.

The spelling of 81947136 in words is "eighty-one million, nine hundred forty-seven thousand, one hundred thirty-six".