21221743 has 2 divisors, whose sum is σ = 21221744. Its totient is φ = 21221742.

The previous prime is 21221741. The next prime is 21221749. The reversal of 21221743 is 34712212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221743 - 2¹ = 21221741 is a prime.

Together with 21221741, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610871 + 10610872.

It is an arithmetic number, because the mean of its divisors is an integer number (10610872).

Almost surely, 2^21221743 is an apocalyptic number.

21221743 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221743 is an equidigital number, since it uses as much as digits as its factorization.

21221743 is an evil number, because the sum of its binary digits is even.

The product of its digits is 672, while the sum is 22.

The square root of 21221743 is about 4606.7063071136. The cubic root of 21221743 is about 276.8600865178.

Adding to 21221743 its reverse (34712212), we get a palindrome (55933955).

The spelling of 21221743 in words is "twenty-one million, two hundred twenty-one thousand, seven hundred forty-three".