21604453 has 6 divisors (see below), whose sum is σ = 23394354. Its totient is φ = 19942416.

The previous prime is 21604439. The next prime is 21604469. The reversal of 21604453 is 35440612.

It can be written as a sum of positive squares in 3 ways, for example, as 232324 + 21372129 = 482^2 + 4623^2 .

It is not a de Polignac number, because 21604453 - 2⁵ = 21604421 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 (21604853) 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 5 ways as a sum of consecutive naturals, for example, 63750 + ... + 64087.

It is an arithmetic number, because the mean of its divisors is an integer number (3899059).

Almost surely, 2^21604453 is an apocalyptic number.

It is an amenable number.

21604453 is a deficient number, since it is larger than the sum of its proper divisors (1789901).

21604453 is a wasteful number, since it uses less digits than its factorization.

21604453 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127863 (or 127850 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 21604453 is about 4648.0590572840. The cubic root of 21604453 is about 278.5144666602.

The spelling of 21604453 in words is "twenty-one million, six hundred four thousand, four hundred fifty-three".