1686808638 has 80 divisors (see below), whose sum is σ = 4151790720. Its totient is φ = 509495184.

The previous prime is 1686808637. The next prime is 1686808727. The reversal of 1686808638 is 8368086861.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1686808631) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 58881 + ... + 82707.

It is an arithmetic number, because the mean of its divisors is an integer number (51897384).

Almost surely, 2^1686808638 is an apocalyptic number.

1686808638 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1686808638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2075895360).

1686808638 is an abundant number, since it is smaller than the sum of its proper divisors (2464982082).

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

1686808638 is a wasteful number, since it uses less digits than its factorization.

1686808638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23883 (or 23874 counting only the distinct ones).

The product of its (nonzero) digits is 2654208, while the sum is 54.

The square root of 1686808638 is about 41070.7759605294. The cubic root of 1686808638 is about 1190.3881788019.

The spelling of 1686808638 in words is "one billion, six hundred eighty-six million, eight hundred eight thousand, six hundred thirty-eight".