21124512 has 72 divisors (see below), whose sum is σ = 61572420. Its totient is φ = 6865920.

The previous prime is 21124501. The next prime is 21124529. The reversal of 21124512 is 21542112.

21124512 is a `hidden beast` number, since 211 + 2 + 451 + 2 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21123216 + 1296 = 4596^2 + 36^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

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, 10914 + ... + 12702.

Almost surely, 2^21124512 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 21124512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30786210).

21124512 is an abundant number, since it is smaller than the sum of its proper divisors (40447908).

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

21124512 is a wasteful number, since it uses less digits than its factorization.

21124512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1846 (or 1835 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 21124512 is about 4596.1409900045. The cubic root of 21124512 is about 276.4366120347.

Adding to 21124512 its reverse (21542112), we get a palindrome (42666624).

The spelling of 21124512 in words is "twenty-one million, one hundred twenty-four thousand, five hundred twelve".