21641305 has 8 divisors (see below), whose sum is σ = 29679552. Its totient is φ = 14839728.

The previous prime is 21641303. The next prime is 21641309. The reversal of 21641305 is 50314612.

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 21641305 - 2¹ = 21641303 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21641303) 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, 309127 + ... + 309196.

It is an arithmetic number, because the mean of its divisors is an integer number (3709944).

Almost surely, 2^21641305 is an apocalyptic number.

It is an amenable number.

21641305 is a deficient number, since it is larger than the sum of its proper divisors (8038247).

21641305 is an equidigital number, since it uses as much as digits as its factorization.

21641305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618335.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21641305 is about 4652.0216035612. The cubic root of 21641305 is about 278.6727362660.

Adding to 21641305 its reverse (50314612), we get a palindrome (71955917).

The spelling of 21641305 in words is "twenty-one million, six hundred forty-one thousand, three hundred five".