21404041421 has 4 divisors (see below), whose sum is σ = 24461761632. Its totient is φ = 18346321212.

The previous prime is 21404041343. The next prime is 21404041427. The reversal of 21404041421 is 12414040412.

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 21404041421 - 2³⁴ = 4224172237 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404041427) 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, 1528860095 + ... + 1528860108.

It is an arithmetic number, because the mean of its divisors is an integer number (6115440408).

Almost surely, 2^21404041421 is an apocalyptic number.

It is an amenable number.

21404041421 is a deficient number, since it is larger than the sum of its proper divisors (3057720211).

21404041421 is an equidigital number, since it uses as much as digits as its factorization.

21404041421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3057720210.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21404041421 its reverse (12414040412), we get a palindrome (33818081833).

The spelling of 21404041421 in words is "twenty-one billion, four hundred four million, forty-one thousand, four hundred twenty-one".