21111087800 has 144 divisors (see below), whose sum is σ = 54120806880. Its totient is φ = 7652620800.

The previous prime is 21111087799. The next prime is 21111087841. The reversal of 21111087800 is 878011112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 8880212 + ... + 8882588.

Almost surely, 2^21111087800 is an apocalyptic number.

21111087800 is a gapful number since it is divisible by the number (20) 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 21111087800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27060403440).

21111087800 is an abundant number, since it is smaller than the sum of its proper divisors (33009719080).

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

21111087800 is a wasteful number, since it uses less digits than its factorization.

21111087800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2782 (or 2762 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 29.

Adding to 21111087800 its reverse (878011112), we get a palindrome (21989098912).

It can be divided in two parts, 211 and 11087800, that added together give a palindrome (11088011).

The spelling of 21111087800 in words is "twenty-one billion, one hundred eleven million, eighty-seven thousand, eight hundred".