81100928 has 32 divisors (see below), whose sum is σ = 164322000. Its totient is φ = 39859456.

The previous prime is 81100919. The next prime is 81100933. The reversal of 81100928 is 82900118.

It is a tau number, because it is divible by the number of its divisors (32).

It is a super-2 number, since 2×81100928² = 13154721044922368, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81100928.

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, 2183 + ... + 12921.

Almost surely, 2^81100928 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 81100928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82161000).

81100928 is an abundant number, since it is smaller than the sum of its proper divisors (83221072).

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

81100928 is a wasteful number, since it uses less digits than its factorization.

81100928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10812 (or 10800 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 81100928 is about 9005.6053655487. The cubic root of 81100928 is about 432.8545043613.

It can be divided in two parts, 81100 and 928, that added together give a palindrome (82028).

The spelling of 81100928 in words is "eighty-one million, one hundred thousand, nine hundred twenty-eight".