21820608 has 84 divisors (see below), whose sum is σ = 64072008. Its totient is φ = 7096320.

The previous prime is 21820597. The next prime is 21820613. The reversal of 21820608 is 80602812.

It is a super-2 number, since 2×21820608² = 952277866979328, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24328 + ... + 25208.

It is an arithmetic number, because the mean of its divisors is an integer number (762762).

Almost surely, 2^21820608 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 21820608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32036004).

21820608 is an abundant number, since it is smaller than the sum of its proper divisors (42251400).

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

21820608 is a wasteful number, since it uses less digits than its factorization.

21820608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 942 (or 929 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21820608 is about 4671.2533649975. The cubic root of 21820608 is about 279.4402422587.

The spelling of 21820608 in words is "twenty-one million, eight hundred twenty thousand, six hundred eight".