21221441 has 2 divisors, whose sum is σ = 21221442. Its totient is φ = 21221440.

The previous prime is 21221429. The next prime is 21221443. The reversal of 21221441 is 14412212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 7862416 = 3655^2 + 2804^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221441 - 2⁶ = 21221377 is a prime.

Together with 21221443, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21221443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610720 + 10610721.

It is an arithmetic number, because the mean of its divisors is an integer number (10610721).

Almost surely, 2^21221441 is an apocalyptic number.

It is an amenable number.

21221441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221441 is an equidigital number, since it uses as much as digits as its factorization.

21221441 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 128, while the sum is 17.

The square root of 21221441 is about 4606.6735286973. The cubic root of 21221441 is about 276.8587732084.

Adding to 21221441 its reverse (14412212), we get a palindrome (35633653).

The spelling of 21221441 in words is "twenty-one million, two hundred twenty-one thousand, four hundred forty-one".