21005472 has 96 divisors (see below), whose sum is σ = 59621184. Its totient is φ = 6451200.

The previous prime is 21005441. The next prime is 21005473. The reversal of 21005472 is 27450012.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005473) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99447 + ... + 99657.

It is an arithmetic number, because the mean of its divisors is an integer number (621054).

Almost surely, 2^21005472 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 21005472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29810592).

21005472 is an abundant number, since it is smaller than the sum of its proper divisors (38615712).

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

21005472 is a wasteful number, since it uses less digits than its factorization.

21005472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302 (or 294 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21005472 is about 4583.1727002154. The cubic root of 21005472 is about 275.9163787842.

Adding to 21005472 its reverse (27450012), we get a palindrome (48455484).

The spelling of 21005472 in words is "twenty-one million, five thousand, four hundred seventy-two".