21861632 has 36 divisors (see below), whose sum is σ = 47001780. Its totient is φ = 10088448.

The previous prime is 21861601. The next prime is 21861649. The reversal of 21861632 is 23616812.

It can be written as a sum of positive squares in 2 ways, for example, as 11723776 + 10137856 = 3424^2 + 3184^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21861595 and 21861604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44 + ... + 6612.

It is an arithmetic number, because the mean of its divisors is an integer number (1305605).

Almost surely, 2^21861632 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 21861632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23500890).

21861632 is an abundant number, since it is smaller than the sum of its proper divisors (25140148).

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

21861632 is an equidigital number, since it uses as much as digits as its factorization.

21861632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6598 (or 6584 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 21861632 is about 4675.6424157542. The cubic root of 21861632 is about 279.6152538780.

The spelling of 21861632 in words is "twenty-one million, eight hundred sixty-one thousand, six hundred thirty-two".