81996736 has 56 divisors (see below), whose sum is σ = 172654976. Its totient is φ = 38568960.

The previous prime is 81996731. The next prime is 81996751. The reversal of 81996736 is 63769918.

It is a self number, because there is not a number n which added to its sum of digits gives 81996736.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81996731) 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, 72850 + ... + 73966.

It is a vampire number, since it can be written as 8936 ⋅ 9176 (with its own digits).

Almost surely, 2^81996736 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 81996736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86327488).

81996736 is an abundant number, since it is smaller than the sum of its proper divisors (90658240).

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

81996736 is a wasteful number, since it uses less digits than its factorization.

81996736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1197 (or 1187 counting only the distinct ones).

The product of its digits is 489888, while the sum is 49.

The square root of 81996736 is about 9055.2049120934. The cubic root of 81996736 is about 434.4423841152.

The spelling of 81996736 in words is "eighty-one million, nine hundred ninety-six thousand, seven hundred thirty-six".