21404453 has 8 divisors (see below), whose sum is σ = 24655872. Its totient is φ = 18201456.

The previous prime is 21404437. The next prime is 21404459. The reversal of 21404453 is 35440412.

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

It is not a de Polignac number, because 21404453 - 2⁴ = 21404437 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 (21404459) 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, 11150 + ... + 12927.

It is an arithmetic number, because the mean of its divisors is an integer number (3081984).

Almost surely, 2^21404453 is an apocalyptic number.

It is an amenable number.

21404453 is a deficient number, since it is larger than the sum of its proper divisors (3251419).

21404453 is a wasteful number, since it uses less digits than its factorization.

21404453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24211.

The product of its (nonzero) digits is 1920, while the sum is 23.

The square root of 21404453 is about 4626.4946773989. The cubic root of 21404453 is about 277.6523655321.

Adding to 21404453 its reverse (35440412), we get a palindrome (56844865).

The spelling of 21404453 in words is "twenty-one million, four hundred four thousand, four hundred fifty-three".