1644557441 has 4 divisors (see below), whose sum is σ = 1741296132. Its totient is φ = 1547818752.

The previous prime is 1644557423. The next prime is 1644557449. The reversal of 1644557441 is 1447554461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1391588416 + 252969025 = 37304^2 + 15905^2 .

It is a cyclic number.

It is not a de Polignac number, because 1644557441 - 2¹⁸ = 1644295297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1644557449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48369320 + ... + 48369353.

It is an arithmetic number, because the mean of its divisors is an integer number (435324033).

Almost surely, 2^1644557441 is an apocalyptic number.

It is an amenable number.

1644557441 is a deficient number, since it is larger than the sum of its proper divisors (96738691).

1644557441 is an equidigital number, since it uses as much as digits as its factorization.

1644557441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96738690.

The product of its digits is 268800, while the sum is 41.

The square root of 1644557441 is about 40553.1434170028. The cubic root of 1644557441 is about 1180.3650697009.

The spelling of 1644557441 in words is "one billion, six hundred forty-four million, five hundred fifty-seven thousand, four hundred forty-one".