1644140405 has 4 divisors (see below), whose sum is σ = 1972968492. Its totient is φ = 1315312320.

The previous prime is 1644140371. The next prime is 1644140419. The reversal of 1644140405 is 5040414461.

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 335292721 + 1308847684 = 18311^2 + 36178^2 .

It is not a de Polignac number, because 1644140405 - 2¹⁰ = 1644139381 is a prime.

It is a super-3 number, since 3×1644140405³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164414036 + ... + 164414045.

It is an arithmetic number, because the mean of its divisors is an integer number (493242123).

Almost surely, 2^1644140405 is an apocalyptic number.

It is an amenable number.

1644140405 is a deficient number, since it is larger than the sum of its proper divisors (328828087).

1644140405 is an equidigital number, since it uses as much as digits as its factorization.

1644140405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328828086.

The product of its (nonzero) digits is 7680, while the sum is 29.

The square root of 1644140405 is about 40548.0012454375. The cubic root of 1644140405 is about 1180.2652867582.

Adding to 1644140405 its reverse (5040414461), we get a palindrome (6684554866).

The spelling of 1644140405 in words is "one billion, six hundred forty-four million, one hundred forty thousand, four hundred five".