1644344666 has 8 divisors (see below), whose sum is σ = 2469377664. Its totient is φ = 821218780.

The previous prime is 1644344659. The next prime is 1644344671. The reversal of 1644344666 is 6664434461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×1644344666³ (a number of 29 digits) contains 333 as substring.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 474620 + ... + 478071.

It is an arithmetic number, because the mean of its divisors is an integer number (308672208).

Almost surely, 2^1644344666 is an apocalyptic number.

1644344666 is a deficient number, since it is larger than the sum of its proper divisors (825032998).

1644344666 is an equidigital number, since it uses as much as digits as its factorization.

1644344666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 953556.

The product of its digits is 995328, while the sum is 44.

The square root of 1644344666 is about 40550.5199226841. The cubic root of 1644344666 is about 1180.3141617781.

The spelling of 1644344666 in words is "one billion, six hundred forty-four million, three hundred forty-four thousand, six hundred sixty-six".