1643631812 has 12 divisors (see below), whose sum is σ = 2876665596. Its totient is φ = 821727360.

The previous prime is 1643631779. The next prime is 1643631817. The reversal of 1643631812 is 2181363461.

It can be written as a sum of positive squares in 2 ways, for example, as 1460462656 + 183169156 = 38216^2 + 13534^2 .

It is not an unprimeable number, because it can be changed into a prime (1643631817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37448 + ... + 68480.

It is an arithmetic number, because the mean of its divisors is an integer number (239722133).

Almost surely, 2^1643631812 is an apocalyptic number.

It is an amenable number.

1643631812 is a deficient number, since it is larger than the sum of its proper divisors (1233033784).

1643631812 is a wasteful number, since it uses less digits than its factorization.

1643631812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44278 (or 44276 counting only the distinct ones).

The product of its digits is 20736, while the sum is 35.

The square root of 1643631812 is about 40541.7292675091. The cubic root of 1643631812 is about 1180.1435744099.

The spelling of 1643631812 in words is "one billion, six hundred forty-three million, six hundred thirty-one thousand, eight hundred twelve".