1644421 has 2 divisors, whose sum is σ = 1644422. Its totient is φ = 1644420.

The previous prime is 1644413. The next prime is 1644437. The reversal of 1644421 is 1244461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1028196 + 616225 = 1014^2 + 785^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644421 - 2³ = 1644413 is a prime.

It is equal to p₁₂₄₂₄₉ and since 1644421 and 124249 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 1644392 and 1644401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1644451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822210 + 822211.

It is an arithmetic number, because the mean of its divisors is an integer number (822211).

2^1644421 is an apocalyptic number.

It is an amenable number.

1644421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644421 is an equidigital number, since it uses as much as digits as its factorization.

1644421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 22.

The square root of 1644421 is about 1282.3497962725. The cubic root of 1644421 is about 118.0332425732.

Adding to 1644421 its reverse (1244461), we get a palindrome (2888882).

The spelling of 1644421 in words is "one million, six hundred forty-four thousand, four hundred twenty-one".