81859544 has 48 divisors (see below), whose sum is σ = 167598720. Its totient is φ = 37464960.

The previous prime is 81859537. The next prime is 81859549. The reversal of 81859544 is 44595818.

It is a junction number, because it is equal to n+sod(n) for n = 81859495 and 81859504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81859549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 258074 + ... + 258390.

It is an arithmetic number, because the mean of its divisors is an integer number (3491640).

Almost surely, 2^81859544 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81859544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (83799360).

81859544 is an abundant number, since it is smaller than the sum of its proper divisors (85739176).

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

81859544 is a wasteful number, since it uses less digits than its factorization.

81859544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540 (or 523 counting only the distinct ones).

The product of its digits is 230400, while the sum is 44.

The square root of 81859544 is about 9047.6264290697. The cubic root of 81859544 is about 434.1999545818.

The spelling of 81859544 in words is "eighty-one million, eight hundred fifty-nine thousand, five hundred forty-four".