1644634666 has 16 divisors (see below), whose sum is σ = 2502327168. Its totient is φ = 810540000.

The previous prime is 1644634627. The next prime is 1644634703. The reversal of 1644634666 is 6664364461.

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 7 ways as a sum of consecutive naturals, for example, 343791 + ... + 348541.

It is an arithmetic number, because the mean of its divisors is an integer number (156395448).

Almost surely, 2^1644634666 is an apocalyptic number.

1644634666 is a deficient number, since it is larger than the sum of its proper divisors (857692502).

1644634666 is a wasteful number, since it uses less digits than its factorization.

1644634666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7197.

The product of its digits is 1492992, while the sum is 46.

The square root of 1644634666 is about 40554.0955514976. The cubic root of 1644634666 is about 1180.3835452420.

The spelling of 1644634666 in words is "one billion, six hundred forty-four million, six hundred thirty-four thousand, six hundred sixty-six".