21124403 has 4 divisors (see below), whose sum is σ = 21170688. Its totient is φ = 21078120.

The previous prime is 21124391. The next prime is 21124459. The reversal of 21124403 is 30442112.

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

It is a cyclic number.

It is not a de Polignac number, because 21124403 - 2⁶ = 21124339 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21124463) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 22451 + ... + 23372.

It is an arithmetic number, because the mean of its divisors is an integer number (5292672).

Almost surely, 2^21124403 is an apocalyptic number.

21124403 is a deficient number, since it is larger than the sum of its proper divisors (46285).

21124403 is an equidigital number, since it uses as much as digits as its factorization.

21124403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46284.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21124403 is about 4596.1291322155. The cubic root of 21124403 is about 276.4361365738.

Adding to 21124403 its reverse (30442112), we get a palindrome (51566515).

The spelling of 21124403 in words is "twenty-one million, one hundred twenty-four thousand, four hundred three".