21111084 has 48 divisors (see below), whose sum is σ = 55910400. Its totient is φ = 6885648.

The previous prime is 21111073. The next prime is 21111113. The reversal of 21111084 is 48011112.

It is a super-4 number, since 4×21111084⁴ (a number of 30 digits) contains 4444 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2997 + ... + 7155.

It is an arithmetic number, because the mean of its divisors is an integer number (1164800).

Almost surely, 2^21111084 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 21111084, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27955200).

21111084 is an abundant number, since it is smaller than the sum of its proper divisors (34799316).

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

21111084 is a wasteful number, since it uses less digits than its factorization.

21111084 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4219 (or 4211 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The square root of 21111084 is about 4594.6799670924. The cubic root of 21111084 is about 276.3780264190.

Adding to 21111084 its reverse (48011112), we get a palindrome (69122196).

It can be divided in two parts, 2111108 and 4, that added together give a palindrome (2111112).

The spelling of 21111084 in words is "twenty-one million, one hundred eleven thousand, eighty-four".