81905936 has 40 divisors (see below), whose sum is σ = 183678720. Its totient is φ = 34654464.

The previous prime is 81905933. The next prime is 81905969. The reversal of 81905936 is 63950918.

It is a junction number, because it is equal to n+sod(n) for n = 81905893 and 81905902.

It is not an unprimeable number, because it can be changed into a prime (81905933) 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, 4220 + ... + 13476.

It is an arithmetic number, because the mean of its divisors is an integer number (4591968).

Almost surely, 2^81905936 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 81905936, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91839360).

81905936 is an abundant number, since it is smaller than the sum of its proper divisors (101772784).

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

81905936 is a wasteful number, since it uses less digits than its factorization.

81905936 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9351 (or 9345 counting only the distinct ones).

The product of its (nonzero) digits is 58320, while the sum is 41.

The square root of 81905936 is about 9050.1898322632. The cubic root of 81905936 is about 434.2819633464.

The spelling of 81905936 in words is "eighty-one million, nine hundred five thousand, nine hundred thirty-six".