81705936 has 80 divisors (see below), whose sum is σ = 237234816. Its totient is φ = 24043008.

The previous prime is 81705931. The next prime is 81705941. The reversal of 81705936 is 63950718.

It is an interprime number because it is at equal distance from previous prime (81705931) and next prime (81705941).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 81705894 and 81705903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81705931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11506 + ... + 17198.

Almost surely, 2^81705936 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 81705936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118617408).

81705936 is an abundant number, since it is smaller than the sum of its proper divisors (155528880).

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

81705936 is a wasteful number, since it uses less digits than its factorization.

81705936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5740 (or 5734 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 39.

The square root of 81705936 is about 9039.1335867991. The cubic root of 81705936 is about 433.9281949912.

The spelling of 81705936 in words is "eighty-one million, seven hundred five thousand, nine hundred thirty-six".