21304621 has 8 divisors (see below), whose sum is σ = 24293304. Its totient is φ = 18508800.

The previous prime is 21304603. The next prime is 21304627. The reversal of 21304621 is 12640312.

It can be written as a sum of positive squares in 4 ways, for example, as 15625 + 21288996 = 125^2 + 4614^2 .

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 21304621 - 2⁹ = 21304109 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 (21304627) 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 7 ways as a sum of consecutive naturals, for example, 47980 + ... + 48421.

It is an arithmetic number, because the mean of its divisors is an integer number (3036663).

Almost surely, 2^21304621 is an apocalyptic number.

It is an amenable number.

21304621 is a deficient number, since it is larger than the sum of its proper divisors (2988683).

21304621 is a wasteful number, since it uses less digits than its factorization.

21304621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96431.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21304621 is about 4615.6929057293. The cubic root of 21304621 is about 277.2200287524.

Adding to 21304621 its reverse (12640312), we get a palindrome (33944933).

The spelling of 21304621 in words is "twenty-one million, three hundred four thousand, six hundred twenty-one".