81785856 has 88 divisors (see below), whose sum is σ = 221403520. Its totient is φ = 26836992.

The previous prime is 81785839. The next prime is 81785863. The reversal of 81785856 is 65858718.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 242520 + ... + 242856.

Almost surely, 2^81785856 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 81785856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110701760).

81785856 is an abundant number, since it is smaller than the sum of its proper divisors (139617664).

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

81785856 is a wasteful number, since it uses less digits than its factorization.

81785856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439 (or 421 counting only the distinct ones).

The product of its digits is 537600, while the sum is 48.

The square root of 81785856 is about 9043.5532839697. The cubic root of 81785856 is about 434.0696300040.

The spelling of 81785856 in words is "eighty-one million, seven hundred eighty-five thousand, eight hundred fifty-six".