821111111128 has 128 divisors (see below), whose sum is σ = 1933666467840. Its totient is φ = 317552400000.

The previous prime is 821111111113. The next prime is 821111111153.

821111111128 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 821111111096 and 821111111105.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 165845053 + ... + 165850003.

It is an arithmetic number, because the mean of its divisors is an integer number (15106769280).

Almost surely, 2^821111111128 is an apocalyptic number.

821111111128 is a gapful number since it is divisible by the number (88) 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 821111111128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (966833233920).

821111111128 is an abundant number, since it is smaller than the sum of its proper divisors (1112555356712).

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

821111111128 is a wasteful number, since it uses less digits than its factorization.

821111111128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6909 (or 6905 counting only the distinct ones).

The product of its digits is 256, while the sum is 28.

It can be divided in two parts, 821111 and 111128, that added together give a palindrome (932239).

The spelling of 821111111128 in words is "eight hundred twenty-one billion, one hundred eleven million, one hundred eleven thousand, one hundred twenty-eight".