81603840 has 144 divisors (see below), whose sum is σ = 264902400. Its totient is φ = 21405696.

The previous prime is 81603829. The next prime is 81603887. The reversal of 81603840 is 4830618.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 81603798 and 81603807.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 303226 + ... + 303494.

It is an arithmetic number, because the mean of its divisors is an integer number (1839600).

Almost surely, 2^81603840 is an apocalyptic number.

81603840 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 81603840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132451200).

81603840 is an abundant number, since it is smaller than the sum of its proper divisors (183298560).

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

81603840 is a wasteful number, since it uses less digits than its factorization.

81603840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 81603840 is about 9033.4843775810. The cubic root of 81603840 is about 433.7473807171.

The spelling of 81603840 in words is "eighty-one million, six hundred three thousand, eight hundred forty".