13221621 has 24 divisors (see below), whose sum is σ = 22276800. Its totient is φ = 7553448.

The previous prime is 13221599. The next prime is 13221623. The reversal of 13221621 is 12612231.

It is not a de Polignac number, because 13221621 - 2⁷ = 13221493 is a prime.

It is a super-2 number, since 2×13221621² = 349622523735282, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 13221594 and 13221603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13221623) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 946 + ... + 5228.

It is an arithmetic number, because the mean of its divisors is an integer number (928200).

Almost surely, 2^13221621 is an apocalyptic number.

It is an amenable number.

13221621 is a deficient number, since it is larger than the sum of its proper divisors (9055179).

13221621 is an equidigital number, since it uses as much as digits as its factorization.

13221621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310 (or 4293 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 13221621 is about 3636.1546996793. The cubic root of 13221621 is about 236.4621140259.

Adding to 13221621 its reverse (12612231), we get a palindrome (25833852).

The spelling of 13221621 in words is "thirteen million, two hundred twenty-one thousand, six hundred twenty-one".