21401424021 has 4 divisors (see below), whose sum is σ = 28535232032. Its totient is φ = 14267616012.

The previous prime is 21401424017. The next prime is 21401424047. The reversal of 21401424021 is 12042410412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21401424021 - 2² = 21401424017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401424001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3566904001 + ... + 3566904006.

It is an arithmetic number, because the mean of its divisors is an integer number (7133808008).

Almost surely, 2^21401424021 is an apocalyptic number.

It is an amenable number.

21401424021 is a deficient number, since it is larger than the sum of its proper divisors (7133808011).

21401424021 is an equidigital number, since it uses as much as digits as its factorization.

21401424021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7133808010.

The product of its (nonzero) digits is 512, while the sum is 21.

Adding to 21401424021 its reverse (12042410412), we get a palindrome (33443834433).

The spelling of 21401424021 in words is "twenty-one billion, four hundred one million, four hundred twenty-four thousand, twenty-one".