21008460 has 96 divisors (see below), whose sum is σ = 64915200. Its totient is φ = 5034240.

The previous prime is 21008459. The next prime is 21008497. The reversal of 21008460 is 6480012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91626 + ... + 91854.

It is an arithmetic number, because the mean of its divisors is an integer number (676200).

Almost surely, 2^21008460 is an apocalyptic number.

21008460 is a gapful number since it is divisible by the number (20) 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 21008460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32457600).

21008460 is an abundant number, since it is smaller than the sum of its proper divisors (43906740).

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

21008460 is a wasteful number, since it uses less digits than its factorization.

21008460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 389 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21008460 is about 4583.4986636848. The cubic root of 21008460 is about 275.9294610745.

Adding to 21008460 its reverse (6480012), we get a palindrome (27488472).

The spelling of 21008460 in words is "twenty-one million, eight thousand, four hundred sixty".