1644205368 has 64 divisors (see below), whose sum is σ = 4439756160. Its totient is φ = 504418176.

The previous prime is 1644205351. The next prime is 1644205397. The reversal of 1644205368 is 8635024461.

It is a super-3 number, since 3×1644205368³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100671 + ... + 115857.

It is an arithmetic number, because the mean of its divisors is an integer number (69371190).

Almost surely, 2^1644205368 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1644205368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2219878080).

1644205368 is an abundant number, since it is smaller than the sum of its proper divisors (2795550792).

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

1644205368 is a wasteful number, since it uses less digits than its factorization.

1644205368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15556 (or 15552 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

The square root of 1644205368 is about 40548.8023004379. The cubic root of 1644205368 is about 1180.2808313682.

The spelling of 1644205368 in words is "one billion, six hundred forty-four million, two hundred five thousand, three hundred sixty-eight".