21280512 has 108 divisors (see below), whose sum is σ = 62525960. Its totient is φ = 6420480.

The previous prime is 21280487. The next prime is 21280529. The reversal of 21280512 is 21508212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 92814 + ... + 93042.

Almost surely, 2^21280512 is an apocalyptic number.

21280512 is a gapful number since it is divisible by the number (22) 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 21280512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31262980).

21280512 is an abundant number, since it is smaller than the sum of its proper divisors (41245448).

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

21280512 is a wasteful number, since it uses less digits than its factorization.

21280512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270 (or 245 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21280512 is about 4613.0805325726. The cubic root of 21280512 is about 277.1154188911.

Adding to 21280512 its reverse (21508212), we get a palindrome (42788724).

The spelling of 21280512 in words is "twenty-one million, two hundred eighty thousand, five hundred twelve".