21643104 has 144 divisors (see below), whose sum is σ = 68257728. Its totient is φ = 5983488.

The previous prime is 21643103. The next prime is 21643117. The reversal of 21643104 is 40134612.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643103) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 202219 + ... + 202325.

It is an arithmetic number, because the mean of its divisors is an integer number (474012).

Almost surely, 2^21643104 is an apocalyptic number.

21643104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21643104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34128864).

21643104 is an abundant number, since it is smaller than the sum of its proper divisors (46614624).

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

21643104 is a wasteful number, since it uses less digits than its factorization.

21643104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 177 (or 162 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21643104 is about 4652.2149563407. The cubic root of 21643104 is about 278.6804578947.

Adding to 21643104 its reverse (40134612), we get a palindrome (61777716).

The spelling of 21643104 in words is "twenty-one million, six hundred forty-three thousand, one hundred four".