81755540 has 24 divisors (see below), whose sum is σ = 171974880. Its totient is φ = 32647328.

The previous prime is 81755539. The next prime is 81755543. The reversal of 81755540 is 4555718.

It is a self number, because there is not a number n which added to its sum of digits gives 81755540.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81755543) 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 7 ways as a sum of consecutive naturals, for example, 10079 + ... + 16281.

It is an arithmetic number, because the mean of its divisors is an integer number (7165620).

Almost surely, 2^81755540 is an apocalyptic number.

It is an amenable number.

81755540 is an abundant number, since it is smaller than the sum of its proper divisors (90219340).

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

81755540 is a wasteful number, since it uses less digits than its factorization.

81755540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6871 (or 6869 counting only the distinct ones).

The product of its (nonzero) digits is 28000, while the sum is 35.

The square root of 81755540 is about 9041.8770175224. The cubic root of 81755540 is about 434.0159904066.

The spelling of 81755540 in words is "eighty-one million, seven hundred fifty-five thousand, five hundred forty".