81755520 has 384 divisors, whose sum is σ = 334886400. Its totient is φ = 16773120.

The previous prime is 81755503. The next prime is 81755539. The reversal of 81755520 is 2555718.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1034841 + ... + 1034919.

It is an arithmetic number, because the mean of its divisors is an integer number (872100).

Almost surely, 2^81755520 is an apocalyptic number.

81755520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81755520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (167443200).

81755520 is an abundant number, since it is smaller than the sum of its proper divisors (253130880).

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

81755520 is a wasteful number, since it uses less digits than its factorization.

81755520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126 (or 107 counting only the distinct ones).

The product of its (nonzero) digits is 14000, while the sum is 33.

The square root of 81755520 is about 9041.8759115573. The cubic root of 81755520 is about 434.0159550152.

It can be divided in two parts, 8175 and 5520, that added together give a triangular number (13695 = T₁₆₅).

The spelling of 81755520 in words is "eighty-one million, seven hundred fifty-five thousand, five hundred twenty".