21451335421 has 4 divisors (see below), whose sum is σ = 21452305600. Its totient is φ = 21450365244.

The previous prime is 21451335317. The next prime is 21451335461. The reversal of 21451335421 is 12453315412.

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 21451335421 - 2²¹ = 21449238269 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 (21451335461) 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, 451131 + ... + 496408.

It is an arithmetic number, because the mean of its divisors is an integer number (5363076400).

Almost surely, 2^21451335421 is an apocalyptic number.

It is an amenable number.

21451335421 is a deficient number, since it is larger than the sum of its proper divisors (970179).

21451335421 is an equidigital number, since it uses as much as digits as its factorization.

21451335421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 970178.

The product of its digits is 14400, while the sum is 31.

The spelling of 21451335421 in words is "twenty-one billion, four hundred fifty-one million, three hundred thirty-five thousand, four hundred twenty-one".