21043400421 has 8 divisors (see below), whose sum is σ = 28088805664. Its totient is φ = 14013464400.

The previous prime is 21043400393. The next prime is 21043400449. The reversal of 21043400421 is 12400434012.

It is an interprime number because it is at equal distance from previous prime (21043400393) and next prime (21043400449).

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

It is not a de Polignac number, because 21043400421 - 2²⁹ = 20506529509 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 (21043400321) 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, 3864130 + ... + 3869571.

It is an arithmetic number, because the mean of its divisors is an integer number (3511100708).

Almost surely, 2^21043400421 is an apocalyptic number.

It is an amenable number.

21043400421 is a deficient number, since it is larger than the sum of its proper divisors (7045405243).

21043400421 is an equidigital number, since it uses as much as digits as its factorization.

21043400421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7734611.

The product of its (nonzero) digits is 768, while the sum is 21.

Adding to 21043400421 its reverse (12400434012), we get a palindrome (33443834433).

The spelling of 21043400421 in words is "twenty-one billion, forty-three million, four hundred thousand, four hundred twenty-one".