1643999144 has 16 divisors (see below), whose sum is σ = 3263822100. Its totient is φ = 773646592.

The previous prime is 1643999143. The next prime is 1643999153. The reversal of 1643999144 is 4419993461.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1431714244 + 212284900 = 37838^2 + 14570^2 .

It is a super-3 number, since 3×1643999144³ (a number of 29 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1643999092 and 1643999101.

It is not an unprimeable number, because it can be changed into a prime (1643999141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6043979 + ... + 6044250.

Almost surely, 2^1643999144 is an apocalyptic number.

It is an amenable number.

1643999144 is a deficient number, since it is larger than the sum of its proper divisors (1619822956).

1643999144 is a wasteful number, since it uses less digits than its factorization.

1643999144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12088252 (or 12088248 counting only the distinct ones).

The product of its digits is 839808, while the sum is 50.

The square root of 1643999144 is about 40546.2593095837. The cubic root of 1643999144 is about 1180.2314838403.

The spelling of 1643999144 in words is "one billion, six hundred forty-three million, nine hundred ninety-nine thousand, one hundred forty-four".