1644355685 has 16 divisors (see below), whose sum is σ = 2387771136. Its totient is φ = 1061230848.

The previous prime is 1644355681. The next prime is 1644355697. The reversal of 1644355685 is 5865534461.

It is not a de Polignac number, because 1644355685 - 2² = 1644355681 is a prime.

It is a super-3 number, since 3×1644355685³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644355681) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1381217 + ... + 1382406.

It is an arithmetic number, because the mean of its divisors is an integer number (149235696).

Almost surely, 2^1644355685 is an apocalyptic number.

It is an amenable number.

1644355685 is a deficient number, since it is larger than the sum of its proper divisors (743415451).

1644355685 is a wasteful number, since it uses less digits than its factorization.

1644355685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2763652.

The product of its digits is 1728000, while the sum is 47.

The square root of 1644355685 is about 40550.6557900116. The cubic root of 1644355685 is about 1180.3167982595.

The spelling of 1644355685 in words is "one billion, six hundred forty-four million, three hundred fifty-five thousand, six hundred eighty-five".