21621632 has 32 divisors (see below), whose sum is σ = 44472000. Its totient is φ = 10460160.

The previous prime is 21621631. The next prime is 21621641. The reversal of 21621632 is 23612612.

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 21621598 and 21621607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621631) 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 3 ways as a sum of consecutive naturals, for example, 1244 + ... + 6692.

It is an arithmetic number, because the mean of its divisors is an integer number (1389750).

Almost surely, 2^21621632 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 21621632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22236000).

21621632 is an abundant number, since it is smaller than the sum of its proper divisors (22850368).

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

21621632 is an equidigital number, since it uses as much as digits as its factorization.

21621632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5494 (or 5482 counting only the distinct ones).

The product of its digits is 864, while the sum is 23.

The square root of 21621632 is about 4649.9066657300. The cubic root of 21621632 is about 278.5882683036.

The spelling of 21621632 in words is "twenty-one million, six hundred twenty-one thousand, six hundred thirty-two".