21413221 has 2 divisors, whose sum is σ = 21413222. Its totient is φ = 21413220.

The previous prime is 21413191. The next prime is 21413243. The reversal of 21413221 is 12231412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19492225 + 1920996 = 4415^2 + 1386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21413221 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21413195 and 21413204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21414221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10706610 + 10706611.

It is an arithmetic number, because the mean of its divisors is an integer number (10706611).

Almost surely, 2^21413221 is an apocalyptic number.

It is an amenable number.

21413221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21413221 is an equidigital number, since it uses as much as digits as its factorization.

21413221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96, while the sum is 16.

The square root of 21413221 is about 4627.4421660351. The cubic root of 21413221 is about 277.6902723422.

Adding to 21413221 its reverse (12231412), we get a palindrome (33644633).

The spelling of 21413221 in words is "twenty-one million, four hundred thirteen thousand, two hundred twenty-one".