687138831786 has 128 divisors (see below), whose sum is σ = 1607710021632. Its totient is φ = 193663008000.

The previous prime is 687138831713. The next prime is 687138831853.

It is a happy number.

687138831786 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 119686876 + ... + 119692616.

It is an arithmetic number, because the mean of its divisors is an integer number (12560234544).

Almost surely, 2^687138831786 is an apocalyptic number.

687138831786 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 687138831786, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (803855010816).

687138831786 is an abundant number, since it is smaller than the sum of its proper divisors (920571189846).

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

687138831786 is a wasteful number, since it uses less digits than its factorization.

687138831786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7948.

The product of its digits is 65028096, while the sum is 66.

The spelling of 687138831786 in words is "six hundred eighty-seven billion, one hundred thirty-eight million, eight hundred thirty-one thousand, seven hundred eighty-six".