21221313 has 16 divisors (see below), whose sum is σ = 29774976. Its totient is φ = 13426560.

The previous prime is 21221303. The next prime is 21221339. The reversal of 21221313 is 31312212.

It is not a de Polignac number, because 21221313 - 2¹⁶ = 21155777 is a prime.

It is a super-3 number, since 3×21221313³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21221292 and 21221301.

It is not an unprimeable number, because it can be changed into a prime (21221303) 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 15 ways as a sum of consecutive naturals, for example, 2220 + ... + 6882.

It is an arithmetic number, because the mean of its divisors is an integer number (1860936).

Almost surely, 2^21221313 is an apocalyptic number.

It is an amenable number.

21221313 is a deficient number, since it is larger than the sum of its proper divisors (8553663).

21221313 is a wasteful number, since it uses less digits than its factorization.

21221313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4744.

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

The square root of 21221313 is about 4606.6596357882. The cubic root of 21221313 is about 276.8582165702.

Adding to 21221313 its reverse (31312212), we get a palindrome (52533525).

It can be divided in two parts, 212213 and 13, that added together give a triangular number (212226 = T₆₅₁).

The spelling of 21221313 in words is "twenty-one million, two hundred twenty-one thousand, three hundred thirteen".