21454421 has 4 divisors (see below), whose sum is σ = 21712992. Its totient is φ = 21195852.

The previous prime is 21454409. The next prime is 21454441. The reversal of 21454421 is 12445412.

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 a de Polignac number, because none of the positive numbers 2^k-21454421 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21454441) 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, 129161 + ... + 129326.

It is an arithmetic number, because the mean of its divisors is an integer number (5428248).

Almost surely, 2^21454421 is an apocalyptic number.

It is an amenable number.

21454421 is a deficient number, since it is larger than the sum of its proper divisors (258571).

21454421 is an equidigital number, since it uses as much as digits as its factorization.

21454421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258570.

The product of its digits is 1280, while the sum is 23.

The square root of 21454421 is about 4631.8917301681. The cubic root of 21454421 is about 277.8682544323.

Adding to 21454421 its reverse (12445412), we get a palindrome (33899833).

Subtracting from 21454421 its reverse (12445412), we obtain a palindrome (9009009).

The spelling of 21454421 in words is "twenty-one million, four hundred fifty-four thousand, four hundred twenty-one".