81525444 has 144 divisors (see below), whose sum is σ = 257760384. Its totient is φ = 19514880.

The previous prime is 81525439. The next prime is 81525449. The reversal of 81525444 is 44452518.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81525439) and next prime (81525449).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (81525449) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 131824 + ... + 132440.

Almost surely, 2^81525444 is an apocalyptic number.

81525444 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81525444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128880192).

81525444 is an abundant number, since it is smaller than the sum of its proper divisors (176234940).

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

81525444 is a wasteful number, since it uses less digits than its factorization.

81525444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 666 (or 653 counting only the distinct ones).

The product of its digits is 25600, while the sum is 33.

The square root of 81525444 is about 9029.1441454880. The cubic root of 81525444 is about 433.6084372777.

It can be divided in two parts, 81 and 525444, that added together give a palindrome (525525).

The spelling of 81525444 in words is "eighty-one million, five hundred twenty-five thousand, four hundred forty-four".