21124406 has 4 divisors (see below), whose sum is σ = 31686612. Its totient is φ = 10562202.

The previous prime is 21124391. The next prime is 21124459. The reversal of 21124406 is 60442112.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5281100 + ... + 5281103.

It is an arithmetic number, because the mean of its divisors is an integer number (7921653).

Almost surely, 2^21124406 is an apocalyptic number.

21124406 is a deficient number, since it is larger than the sum of its proper divisors (10562206).

21124406 is a wasteful number, since it uses less digits than its factorization.

21124406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10562205.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21124406 is about 4596.1294585771. The cubic root of 21124406 is about 276.4361496599.

Adding to 21124406 its reverse (60442112), we get a palindrome (81566518).

The spelling of 21124406 in words is "twenty-one million, one hundred twenty-four thousand, four hundred six".