81958912 has 48 divisors (see below), whose sum is σ = 187321680. Its totient is φ = 35119104.

The previous prime is 81958907. The next prime is 81958937. The reversal of 81958912 is 21985918.

It is a congruent number.

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, 11478 + ... + 17194.

It is an arithmetic number, because the mean of its divisors is an integer number (3902535).

Almost surely, 2^81958912 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 81958912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93660840).

81958912 is an abundant number, since it is smaller than the sum of its proper divisors (105362768).

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

81958912 is an equidigital number, since it uses as much as digits as its factorization.

81958912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5746 (or 5726 counting only the distinct ones).

The product of its digits is 51840, while the sum is 43.

The square root of 81958912 is about 9053.1161485977. The cubic root of 81958912 is about 434.3755730165.

The spelling of 81958912 in words is "eighty-one million, nine hundred fifty-eight thousand, nine hundred twelve".