21023424421 has 4 divisors (see below), whose sum is σ = 21512341312. Its totient is φ = 20534507532.

The previous prime is 21023424407. The next prime is 21023424427. The reversal of 21023424421 is 12442432012.

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 a cyclic number.

It is not a de Polignac number, because 21023424421 - 2⁷ = 21023424293 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 (21023424427) 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, 244458381 + ... + 244458466.

It is an arithmetic number, because the mean of its divisors is an integer number (5378085328).

Almost surely, 2^21023424421 is an apocalyptic number.

It is an amenable number.

21023424421 is a deficient number, since it is larger than the sum of its proper divisors (488916891).

21023424421 is an equidigital number, since it uses as much as digits as its factorization.

21023424421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 488916890.

The product of its (nonzero) digits is 3072, while the sum is 25.

Adding to 21023424421 its reverse (12442432012), we get a palindrome (33465856433).

The spelling of 21023424421 in words is "twenty-one billion, twenty-three million, four hundred twenty-four thousand, four hundred twenty-one".