4400021 has 2 divisors, whose sum is σ = 4400022. Its totient is φ = 4400020.

The previous prime is 4399987. The next prime is 4400023. The reversal of 4400021 is 1200044.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4363921 + 36100 = 2089^2 + 190^2 .

It is a cyclic number.

It is not a de Polignac number, because 4400021 - 2¹⁰ = 4398997 is a prime.

Together with 4400023, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 4399975 and 4400011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4400023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2200010 + 2200011.

It is an arithmetic number, because the mean of its divisors is an integer number (2200011).

Almost surely, 2^4400021 is an apocalyptic number.

It is an amenable number.

4400021 is a deficient number, since it is larger than the sum of its proper divisors (1).

4400021 is an equidigital number, since it uses as much as digits as its factorization.

4400021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 4400021 is about 2097.6227020129. The cubic root of 4400021 is about 163.8645148128.

Adding to 4400021 its reverse (1200044), we get a palindrome (5600065).

The spelling of 4400021 in words is "four million, four hundred thousand, twenty-one".