81588240 has 120 divisors (see below), whose sum is σ = 279946368. Its totient is φ = 21285120.

The previous prime is 81588217. The next prime is 81588251. The reversal of 81588240 is 4288518.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81588195 and 81588204.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32635 + ... + 35045.

Almost surely, 2^81588240 is an apocalyptic number.

81588240 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 81588240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139973184).

81588240 is an abundant number, since it is smaller than the sum of its proper divisors (198358128).

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

81588240 is a wasteful number, since it uses less digits than its factorization.

81588240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2477 (or 2468 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 36.

The square root of 81588240 is about 9032.6208821139. The cubic root of 81588240 is about 433.7197394919.

The spelling of 81588240 in words is "eighty-one million, five hundred eighty-eight thousand, two hundred forty".