81440544 has 48 divisors (see below), whose sum is σ = 214613280. Its totient is φ = 27041280.

The previous prime is 81440543. The next prime is 81440561. The reversal of 81440544 is 44504418.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-3 number, since 3×81440544³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81440543) by changing a digit.

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, 25467 + ... + 28485.

It is an arithmetic number, because the mean of its divisors is an integer number (4471110).

Almost surely, 2^81440544 is an apocalyptic number.

It is an amenable number.

81440544 is an abundant number, since it is smaller than the sum of its proper divisors (133172736).

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

81440544 is a wasteful number, since it uses less digits than its factorization.

81440544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3313 (or 3305 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 30.

The square root of 81440544 is about 9024.4414785625. The cubic root of 81440544 is about 433.4578661146.

The spelling of 81440544 in words is "eighty-one million, four hundred forty thousand, five hundred forty-four".