1644561656 has 32 divisors (see below), whose sum is σ = 3200695680. Its totient is φ = 791337600.

The previous prime is 1644561599. The next prime is 1644561661. The reversal of 1644561656 is 6561654461.

It is a congruent number.

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, 26570 + ... + 63206.

It is an arithmetic number, because the mean of its divisors is an integer number (100021740).

Almost surely, 2^1644561656 is an apocalyptic number.

It is an amenable number.

1644561656 is a deficient number, since it is larger than the sum of its proper divisors (1556134024).

1644561656 is a wasteful number, since it uses less digits than its factorization.

1644561656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36855 (or 36851 counting only the distinct ones).

The product of its digits is 518400, while the sum is 44.

The square root of 1644561656 is about 40553.1953858139. The cubic root of 1644561656 is about 1180.3660781251.

The spelling of 1644561656 in words is "one billion, six hundred forty-four million, five hundred sixty-one thousand, six hundred fifty-six".