21005448 has 32 divisors (see below), whose sum is σ = 53796960. Its totient is φ = 6830720.

The previous prime is 21005441. The next prime is 21005473. The reversal of 21005448 is 84450012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21005441) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9690 + ... + 11657.

It is an arithmetic number, because the mean of its divisors is an integer number (1681155).

Almost surely, 2^21005448 is an apocalyptic number.

It is an amenable number.

21005448 is an abundant number, since it is smaller than the sum of its proper divisors (32791512).

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

21005448 is a wasteful number, since it uses less digits than its factorization.

21005448 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21397 (or 21393 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21005448 is about 4583.1700819411. The cubic root of 21005448 is about 275.9162737005.

The spelling of 21005448 in words is "twenty-one million, five thousand, four hundred forty-eight".