21453121 has 4 divisors (see below), whose sum is σ = 21607600. Its totient is φ = 21298644.

The previous prime is 21453119. The next prime is 21453143. The reversal of 21453121 is 12135412.

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 21453121 - 2¹ = 21453119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21453101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77031 + ... + 77308.

It is an arithmetic number, because the mean of its divisors is an integer number (5401900).

Almost surely, 2^21453121 is an apocalyptic number.

It is an amenable number.

21453121 is a deficient number, since it is larger than the sum of its proper divisors (154479).

21453121 is a wasteful number, since it uses less digits than its factorization.

21453121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154478.

The product of its digits is 240, while the sum is 19.

The square root of 21453121 is about 4631.7513966101. The cubic root of 21453121 is about 277.8626419756.

Adding to 21453121 its reverse (12135412), we get a palindrome (33588533).

It can be divided in two parts, 214 and 53121, that added together give a palindrome (53335).

The spelling of 21453121 in words is "twenty-one million, four hundred fifty-three thousand, one hundred twenty-one".