21204345 has 8 divisors (see below), whose sum is σ = 33926976. Its totient is φ = 11308976.

The previous prime is 21204329. The next prime is 21204347. The reversal of 21204345 is 54340212.

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

It is a cyclic number.

It is not a de Polignac number, because 21204345 - 2⁴ = 21204329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21204347) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 706797 + ... + 706826.

It is an arithmetic number, because the mean of its divisors is an integer number (4240872).

Almost surely, 2^21204345 is an apocalyptic number.

It is an amenable number.

21204345 is a deficient number, since it is larger than the sum of its proper divisors (12722631).

21204345 is a wasteful number, since it uses less digits than its factorization.

21204345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1413631.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21204345 is about 4604.8175859636. The cubic root of 21204345 is about 276.7844073949.

Adding to 21204345 its reverse (54340212), we get a palindrome (75544557).

The spelling of 21204345 in words is "twenty-one million, two hundred four thousand, three hundred forty-five".