81128100 has 144 divisors (see below), whose sum is σ = 253594880. Its totient is φ = 19958400.

The previous prime is 81128093. The next prime is 81128123. The reversal of 81128100 is 182118.

It is a super-2 number, since 2×81128100² = 13163537219220000, which contains 22 as substring.

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, 244935 + ... + 245265.

Almost surely, 2^81128100 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 81128100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126797440).

81128100 is an abundant number, since it is smaller than the sum of its proper divisors (172466780).

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

81128100 is a wasteful number, since it uses less digits than its factorization.

81128100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410 (or 403 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 81128100 is about 9007.1138551703. The cubic root of 81128100 is about 432.9028400569.

The spelling of 81128100 in words is "eighty-one million, one hundred twenty-eight thousand, one hundred".