21124436 has 12 divisors (see below), whose sum is σ = 37011828. Its totient is φ = 10549632.

The previous prime is 21124391. The next prime is 21124459. The reversal of 21124436 is 63442112.

It can be written as a sum of positive squares in 2 ways, for example, as 17724100 + 3400336 = 4210^2 + 1844^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1340 + ... + 6636.

It is an arithmetic number, because the mean of its divisors is an integer number (3084319).

Almost surely, 2^21124436 is an apocalyptic number.

It is an amenable number.

21124436 is a deficient number, since it is larger than the sum of its proper divisors (15887392).

21124436 is a wasteful number, since it uses less digits than its factorization.

21124436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6298 (or 6296 counting only the distinct ones).

The product of its digits is 1152, while the sum is 23.

The square root of 21124436 is about 4596.1327221916. The cubic root of 21124436 is about 276.4362805208.

Adding to 21124436 its reverse (63442112), we get a palindrome (84566548).

The spelling of 21124436 in words is "twenty-one million, one hundred twenty-four thousand, four hundred thirty-six".