21111608 has 64 divisors (see below), whose sum is σ = 48591360. Its totient is φ = 8401536.

The previous prime is 21111533. The next prime is 21111611. The reversal of 21111608 is 80611112.

It is a self number, because there is not a number n which added to its sum of digits gives 21111608.

It is a congruent number.

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, 47435 + ... + 47877.

It is an arithmetic number, because the mean of its divisors is an integer number (759240).

Almost surely, 2^21111608 is an apocalyptic number.

21111608 is a gapful number since it is divisible by the number (28) 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 21111608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24295680).

21111608 is an abundant number, since it is smaller than the sum of its proper divisors (27479752).

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

21111608 is a wasteful number, since it uses less digits than its factorization.

21111608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516 (or 512 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 20.

The square root of 21111608 is about 4594.7369892084. The cubic root of 21111608 is about 276.3803130676.

The spelling of 21111608 in words is "twenty-one million, one hundred eleven thousand, six hundred eight".