81124440 has 32 divisors (see below), whose sum is σ = 243373680. Its totient is φ = 21633152.

The previous prime is 81124429. The next prime is 81124447. The reversal of 81124440 is 4442118.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 81124440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81124447) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 337899 + ... + 338138.

Almost surely, 2^81124440 is an apocalyptic number.

It is an amenable number.

81124440 is an abundant number, since it is smaller than the sum of its proper divisors (162249240).

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

81124440 is a wasteful number, since it uses less digits than its factorization.

81124440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676051 (or 676047 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 24.

The square root of 81124440 is about 9006.9106801389. The cubic root of 81124440 is about 432.8963299894.

Adding to 81124440 its reverse (4442118), we get a palindrome (85566558).

The spelling of 81124440 in words is "eighty-one million, one hundred twenty-four thousand, four hundred forty".