1686917385 has 24 divisors (see below), whose sum is σ = 3024819720. Its totient is φ = 868664832.

The previous prime is 1686917371. The next prime is 1686917387. The reversal of 1686917385 is 5837196861.

It can be written as a sum of positive squares in 4 ways, for example, as 101364624 + 1585552761 = 10068^2 + 39819^2 .

It is not a de Polignac number, because 1686917385 - 2⁹ = 1686916873 is a prime.

It is a super-3 number, since 3×1686917385³ (a number of 29 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1686917387) 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 23 ways as a sum of consecutive naturals, for example, 645024 + ... + 647633.

It is an arithmetic number, because the mean of its divisors is an integer number (126034155).

Almost surely, 2^1686917385 is an apocalyptic number.

1686917385 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1686917385 is a deficient number, since it is larger than the sum of its proper divisors (1337902335).

1686917385 is a wasteful number, since it uses less digits than its factorization.

1686917385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1292697 (or 1292694 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 54.

The square root of 1686917385 is about 41072.0998367505. The cubic root of 1686917385 is about 1190.4137593288.

The spelling of 1686917385 in words is "one billion, six hundred eighty-six million, nine hundred seventeen thousand, three hundred eighty-five".