1644789136 has 15 divisors (see below), whose sum is σ = 3187093291. Its totient is φ = 822313456.

The previous prime is 1644789119. The next prime is 1644789137. The reversal of 1644789136 is 6319874461.

The square root of 1644789136 is 40556.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1644789136.

It is not an unprimeable number, because it can be changed into a prime (1644789137) 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 2 ways as a sum of consecutive naturals, for example, 157155 + ... + 167293.

Almost surely, 2^1644789136 is an apocalyptic number.

1644789136 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

1644789136 is the 40556-th square number.

It is an amenable number.

1644789136 is a deficient number, since it is larger than the sum of its proper divisors (1542304155).

1644789136 is an frugal number, since it uses more digits than its factorization.

1644789136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20286 (or 10141 counting only the distinct ones).

The product of its digits is 870912, while the sum is 49.

The cubic root of 1644789136 is about 1180.4204993737.

Multiplying 1644789136 by its sum of digits (49), we get a square (80594667664 = 283892²).

The spelling of 1644789136 in words is "one billion, six hundred forty-four million, seven hundred eighty-nine thousand, one hundred thirty-six".