81825440 has 24 divisors (see below), whose sum is σ = 193312980. Its totient is φ = 32730112.

The previous prime is 81825439. The next prime is 81825451. The reversal of 81825440 is 4452818.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 81072016 + 753424 = 9004^2 + 868^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 81825397 and 81825406.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255545 + ... + 255864.

Almost surely, 2^81825440 is an apocalyptic number.

81825440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81825440 is an abundant number, since it is smaller than the sum of its proper divisors (111487540).

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

81825440 is a wasteful number, since it uses less digits than its factorization.

81825440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511424 (or 511416 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 32.

The square root of 81825440 is about 9045.7415395312. The cubic root of 81825440 is about 434.1396479826.

The spelling of 81825440 in words is "eighty-one million, eight hundred twenty-five thousand, four hundred forty".