21424203252421 has 8 divisors (see below), whose sum is σ = 21775583717888. Its totient is φ = 21072828078000.

The previous prime is 21424203252409. The next prime is 21424203252433. The reversal of 21424203252421 is 12425230242412.

It is an interprime number because it is at equal distance from previous prime (21424203252409) and next prime (21424203252433).

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

It is not a de Polignac number, because 21424203252421 - 2⁷ = 21424203252293 is a prime.

It is a super-2 number, since 2×21424203252421² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424203252521) 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, 7299016 + ... + 9804286.

It is an arithmetic number, because the mean of its divisors is an integer number (2721947964736).

Almost surely, 2^{21424203252421} is an apocalyptic number.

It is an amenable number.

21424203252421 is a deficient number, since it is larger than the sum of its proper divisors (351380465467).

21424203252421 is a wasteful number, since it uses less digits than its factorization.

21424203252421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2645523.

The product of its (nonzero) digits is 61440, while the sum is 34.

Adding to 21424203252421 its reverse (12425230242412), we get a palindrome (33849433494833).

The spelling of 21424203252421 in words is "twenty-one trillion, four hundred twenty-four billion, two hundred three million, two hundred fifty-two thousand, four hundred twenty-one".