1644279728 has 40 divisors (see below), whose sum is σ = 3920978208. Its totient is φ = 650483712.

The previous prime is 1644279727. The next prime is 1644279733. The reversal of 1644279728 is 8279724461.

It is a happy number.

It is a super-3 number, since 3×1644279728³ (a number of 29 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1644279727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 563201 + ... + 566112.

Almost surely, 2^1644279728 is an apocalyptic number.

It is an amenable number.

1644279728 is an abundant number, since it is smaller than the sum of its proper divisors (2276698480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1644279728 is a wasteful number, since it uses less digits than its factorization.

1644279728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129341 (or 1129335 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 50.

The square root of 1644279728 is about 40549.7192098786. The cubic root of 1644279728 is about 1180.2986240279.

The spelling of 1644279728 in words is "one billion, six hundred forty-four million, two hundred seventy-nine thousand, seven hundred twenty-eight".