81109440 has 84 divisors (see below), whose sum is σ = 278992584. Its totient is φ = 21628416.

The previous prime is 81109429. The next prime is 81109447. The reversal of 81109440 is 4490118.

It is a super-2 number, since 2×81109440² = 13157482514227200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81109447) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 11202 + ... + 16961.

Almost surely, 2^81109440 is an apocalyptic number.

81109440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81109440 is an abundant number, since it is smaller than the sum of its proper divisors (197883144).

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

81109440 is a wasteful number, since it uses less digits than its factorization.

81109440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28186 (or 28173 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 81109440 is about 9006.0779476973. The cubic root of 81109440 is about 432.8696473390.

Adding to 81109440 its reverse (4490118), we get a palindrome (85599558).

The spelling of 81109440 in words is "eighty-one million, one hundred nine thousand, four hundred forty".