1644779812 has 12 divisors (see below), whose sum is σ = 3099777436. Its totient is φ = 759129120.

The previous prime is 1644779809. The next prime is 1644779837. The reversal of 1644779812 is 2189774461.

It can be written as a sum of positive squares in 2 ways, for example, as 440412196 + 1204367616 = 20986^2 + 34704^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15815139 + ... + 15815242.

Almost surely, 2^1644779812 is an apocalyptic number.

It is an amenable number.

1644779812 is a deficient number, since it is larger than the sum of its proper divisors (1454997624).

1644779812 is a wasteful number, since it uses less digits than its factorization.

1644779812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31630398 (or 31630396 counting only the distinct ones).

The product of its digits is 677376, while the sum is 49.

The square root of 1644779812 is about 40555.8850476722. The cubic root of 1644779812 is about 1180.4182688423.

It can be divided in two parts, 1644 and 779812, that added together give a square (781456 = 884²).

The spelling of 1644779812 in words is "one billion, six hundred forty-four million, seven hundred seventy-nine thousand, eight hundred twelve".