81091040 has 48 divisors (see below), whose sum is σ = 197769600. Its totient is φ = 31388160.

The previous prime is 81091019. The next prime is 81091061. The reversal of 81091040 is 4019018.

It is an interprime number because it is at equal distance from previous prime (81091019) and next prime (81091061).

It is a junction number, because it is equal to n+sod(n) for n = 81090997 and 81091015.

It is a congruent number.

It is an unprimeable number.

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, 3215 + ... + 13134.

It is an arithmetic number, because the mean of its divisors is an integer number (4120200).

Almost surely, 2^81091040 is an apocalyptic number.

81091040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81091040 is an abundant number, since it is smaller than the sum of its proper divisors (116678560).

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

81091040 is a wasteful number, since it uses less digits than its factorization.

81091040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16395 (or 16387 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 81091040 is about 9005.0563574028. The cubic root of 81091040 is about 432.8369121282.

The spelling of 81091040 in words is "eighty-one million, ninety-one thousand, forty".