21404203021 has 8 divisors (see below), whose sum is σ = 21503563704. Its totient is φ = 21305007360.

The previous prime is 21404202947. The next prime is 21404203033. The reversal of 21404203021 is 12030240412.

It can be written as a sum of positive squares in 4 ways, for example, as 4901796 + 21399301225 = 2214^2 + 146285^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21404203021 - 2⁷ = 21404202893 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21404203021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404203061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 222651 + ... + 303943.

It is an arithmetic number, because the mean of its divisors is an integer number (2687945463).

Almost surely, 2^21404203021 is an apocalyptic number.

It is an amenable number.

21404203021 is a deficient number, since it is larger than the sum of its proper divisors (99360683).

21404203021 is an equidigital number, since it uses as much as digits as its factorization.

21404203021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82511.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21404203021 its reverse (12030240412), we get a palindrome (33434443433).

The spelling of 21404203021 in words is "twenty-one billion, four hundred four million, two hundred three thousand, twenty-one".