4221421 has 2 divisors, whose sum is σ = 4221422. Its totient is φ = 4221420.

The previous prime is 4221419. The next prime is 4221433. The reversal of 4221421 is 1241224.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2924100 + 1297321 = 1710^2 + 1139^2 .

It is a cyclic number.

It is not a de Polignac number, because 4221421 - 2¹ = 4221419 is a prime.

Together with 4221419, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 4221395 and 4221404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4221521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2110710 + 2110711.

It is an arithmetic number, because the mean of its divisors is an integer number (2110711).

Almost surely, 2^4221421 is an apocalyptic number.

It is an amenable number.

4221421 is a deficient number, since it is larger than the sum of its proper divisors (1).

4221421 is an equidigital number, since it uses as much as digits as its factorization.

4221421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 128, while the sum is 16.

The square root of 4221421 is about 2054.6096952949. The cubic root of 4221421 is about 161.6166952697.

Adding to 4221421 its reverse (1241224), we get a palindrome (5462645).

The spelling of 4221421 in words is "four million, two hundred twenty-one thousand, four hundred twenty-one".