21404401421 has 8 divisors (see below), whose sum is σ = 23059606584. Its totient is φ = 19750440960.

The previous prime is 21404401363. The next prime is 21404401433. The reversal of 21404401421 is 12410440412.

It can be written as a sum of positive squares in 4 ways, for example, as 63282025 + 21341119396 = 7955^2 + 146086^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21404401421 - 2⁶ = 21404401357 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 (21404401451) 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, 275300 + ... + 344381.

It is an arithmetic number, because the mean of its divisors is an integer number (2882450823).

Almost surely, 2^21404401421 is an apocalyptic number.

It is an amenable number.

21404401421 is a deficient number, since it is larger than the sum of its proper divisors (1655205163).

21404401421 is a wasteful number, since it uses less digits than its factorization.

21404401421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622351.

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

Adding to 21404401421 its reverse (12410440412), we get a palindrome (33814841833).

The spelling of 21404401421 in words is "twenty-one billion, four hundred four million, four hundred one thousand, four hundred twenty-one".