21060321 has 4 divisors (see below), whose sum is σ = 28080432. Its totient is φ = 14040212.

The previous prime is 21060317. The next prime is 21060329. The reversal of 21060321 is 12306012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21060321 - 2² = 21060317 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21060321.

It is not an unprimeable number, because it can be changed into a prime (21060329) 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 3 ways as a sum of consecutive naturals, for example, 3510051 + ... + 3510056.

It is an arithmetic number, because the mean of its divisors is an integer number (7020108).

Almost surely, 2^21060321 is an apocalyptic number.

It is an amenable number.

21060321 is a deficient number, since it is larger than the sum of its proper divisors (7020111).

21060321 is an equidigital number, since it uses as much as digits as its factorization.

21060321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7020110.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21060321 is about 4589.1525361443. The cubic root of 21060321 is about 276.1563255347.

Adding to 21060321 its reverse (12306012), we get a palindrome (33366333).

The spelling of 21060321 in words is "twenty-one million, sixty thousand, three hundred twenty-one".