81858924 has 144 divisors (see below), whose sum is σ = 250967808. Its totient is φ = 22845888.

The previous prime is 81858923. The next prime is 81858943. The reversal of 81858924 is 42985818.

It is a happy number.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 81858924.

It is not an unprimeable number, because it can be changed into a prime (81858923) 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 47 ways as a sum of consecutive naturals, for example, 360499 + ... + 360725.

It is an arithmetic number, because the mean of its divisors is an integer number (1742832).

Almost surely, 2^81858924 is an apocalyptic number.

81858924 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 81858924, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125483904).

81858924 is an abundant number, since it is smaller than the sum of its proper divisors (169108884).

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

81858924 is a wasteful number, since it uses less digits than its factorization.

81858924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 292 counting only the distinct ones).

The product of its digits is 184320, while the sum is 45.

The square root of 81858924 is about 9047.5921658749. The cubic root of 81858924 is about 434.1988583763.

The spelling of 81858924 in words is "eighty-one million, eight hundred fifty-eight thousand, nine hundred twenty-four".