21402304421 has 4 divisors (see below), whose sum is σ = 21402795744. Its totient is φ = 21401813100.

The previous prime is 21402304409. The next prime is 21402304481. The reversal of 21402304421 is 12440320412.

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 21402304421 - 2²² = 21398110117 is a prime.

It is a super-2 number, since 2×21402304421² (a number of 21 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 (21402304481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 173195 + ... + 269816.

It is an arithmetic number, because the mean of its divisors is an integer number (5350698936).

Almost surely, 2^21402304421 is an apocalyptic number.

It is an amenable number.

21402304421 is a deficient number, since it is larger than the sum of its proper divisors (491323).

21402304421 is an equidigital number, since it uses as much as digits as its factorization.

21402304421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 491322.

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 21402304421 its reverse (12440320412), we get a palindrome (33842624833).

The spelling of 21402304421 in words is "twenty-one billion, four hundred two million, three hundred four thousand, four hundred twenty-one".