21809632 has 48 divisors (see below), whose sum is σ = 46781280. Its totient is φ = 9948672.

The previous prime is 21809621. The next prime is 21809633. The reversal of 21809632 is 23690812.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21809594 and 21809603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21809633) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 42594 + ... + 43102.

It is an arithmetic number, because the mean of its divisors is an integer number (974610).

Almost surely, 2^21809632 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 21809632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23390640).

21809632 is an abundant number, since it is smaller than the sum of its proper divisors (24971648).

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

21809632 is a wasteful number, since it uses less digits than its factorization.

21809632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635 (or 627 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21809632 is about 4670.0783719334. The cubic root of 21809632 is about 279.3933805870.

The spelling of 21809632 in words is "twenty-one million, eight hundred nine thousand, six hundred thirty-two".