81960900 has 144 divisors (see below), whose sum is σ = 279982080. Its totient is φ = 18115200.

The previous prime is 81960871. The next prime is 81960913. The reversal of 81960900 is 906918.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 64471 + ... + 65729.

It is an arithmetic number, because the mean of its divisors is an integer number (1944320).

Almost surely, 2^81960900 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 81960900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139991040).

81960900 is an abundant number, since it is smaller than the sum of its proper divisors (198021180).

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

81960900 is a wasteful number, since it uses less digits than its factorization.

81960900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1314 (or 1307 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 81960900 is about 9053.2259443803. The cubic root of 81960900 is about 434.3790850676.

The spelling of 81960900 in words is "eighty-one million, nine hundred sixty thousand, nine hundred".