81755856 has 240 divisors, whose sum is σ = 298980864. Its totient is φ = 20238336.

The previous prime is 81755851. The next prime is 81755893. The reversal of 81755856 is 65855718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81755851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 222585 + ... + 222951.

Almost surely, 2^81755856 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 81755856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149490432).

81755856 is an abundant number, since it is smaller than the sum of its proper divisors (217225008).

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

81755856 is a wasteful number, since it uses less digits than its factorization.

81755856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418 (or 409 counting only the distinct ones).

The product of its digits is 336000, while the sum is 45.

The square root of 81755856 is about 9041.8944917534. The cubic root of 81755856 is about 434.0165495894.

The spelling of 81755856 in words is "eighty-one million, seven hundred fifty-five thousand, eight hundred fifty-six".