1685781216 has 144 divisors (see below), whose sum is σ = 5490785664. Its totient is φ = 480598272.

The previous prime is 1685781191. The next prime is 1685781221. The reversal of 1685781216 is 6121875861.

1685781216 is a `hidden beast` number, since 1 + 68 + 578 + 1 + 2 + 16 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-3 number, since 3×1685781216³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1779655 + ... + 1780601.

It is an arithmetic number, because the mean of its divisors is an integer number (38130456).

Almost surely, 2^1685781216 is an apocalyptic number.

1685781216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1685781216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2745392832).

1685781216 is an abundant number, since it is smaller than the sum of its proper divisors (3805004448).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1685781216 is a wasteful number, since it uses less digits than its factorization.

1685781216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1853 (or 1842 counting only the distinct ones).

The product of its digits is 161280, while the sum is 45.

The square root of 1685781216 is about 41058.2661104923. The cubic root of 1685781216 is about 1190.1464443271.

The spelling of 1685781216 in words is "one billion, six hundred eighty-five million, seven hundred eighty-one thousand, two hundred sixteen".