81093440 has 28 divisors (see below), whose sum is σ = 193104516. Its totient is φ = 32437248.

The previous prime is 81093413. The next prime is 81093457. The reversal of 81093440 is 4439018.

It can be written as a sum of positive squares in 2 ways, for example, as 20502784 + 60590656 = 4528^2 + 7784^2 .

It is a super-2 number, since 2×81093440² = 13152292022067200, which contains 22 as substring.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

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 3 ways as a sum of consecutive naturals, for example, 126389 + ... + 127028.

Almost surely, 2^81093440 is an apocalyptic number.

81093440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81093440 is an abundant number, since it is smaller than the sum of its proper divisors (112011076).

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

81093440 is a wasteful number, since it uses less digits than its factorization.

81093440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253434 (or 253424 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 81093440 is about 9005.1896148832. The cubic root of 81093440 is about 432.8411822191.

The spelling of 81093440 in words is "eighty-one million, ninety-three thousand, four hundred forty".