21221741 has 2 divisors, whose sum is σ = 21221742. Its totient is φ = 21221740.

The previous prime is 21221731. The next prime is 21221743. The reversal of 21221741 is 14712212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19669225 + 1552516 = 4435^2 + 1246^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221741 - 2¹⁸ = 20959597 is a prime.

It is a Sophie Germain prime.

Together with 21221743, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221743) 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 as a sum of consecutive naturals, namely, 10610870 + 10610871.

It is an arithmetic number, because the mean of its divisors is an integer number (10610871).

Almost surely, 2^21221741 is an apocalyptic number.

It is an amenable number.

21221741 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221741 is an equidigital number, since it uses as much as digits as its factorization.

21221741 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 224, while the sum is 20.

The square root of 21221741 is about 4606.7060900387. The cubic root of 21221741 is about 276.8600778204.

Adding to 21221741 its reverse (14712212), we get a palindrome (35933953).

The spelling of 21221741 in words is "twenty-one million, two hundred twenty-one thousand, seven hundred forty-one".