21906608 has 40 divisors (see below), whose sum is σ = 46010448. Its totient is φ = 10063872.

The previous prime is 21906607. The next prime is 21906613. The reversal of 21906608 is 80660912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21906607) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10760 + ... + 12632.

Almost surely, 2^21906608 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 21906608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23005224).

21906608 is an abundant number, since it is smaller than the sum of its proper divisors (24103840).

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

21906608 is a wasteful number, since it uses less digits than its factorization.

21906608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1941 (or 1935 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 21906608 is about 4680.4495510581. The cubic root of 21906608 is about 279.8068736269.

The spelling of 21906608 in words is "twenty-one million, nine hundred six thousand, six hundred eight".