678856686522 has 128 divisors (see below), whose sum is σ = 1669350187008. Its totient is φ = 179626137600.

The previous prime is 678856686419. The next prime is 678856686523. The reversal of 678856686522 is 225686658876.

It is not an unprimeable number, because it can be changed into a prime (678856686523) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 26398723 + ... + 26424425.

It is an arithmetic number, because the mean of its divisors is an integer number (13041798336).

Almost surely, 2^678856686522 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 678856686522, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (834675093504).

678856686522 is an abundant number, since it is smaller than the sum of its proper divisors (990493500486).

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

678856686522 is a wasteful number, since it uses less digits than its factorization.

678856686522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26324.

The product of its digits is 464486400, while the sum is 69.

It can be divided in two parts, 678856 and 686522, that added together give a triangular number (1365378 = T₁₆₅₂).

The spelling of 678856686522 in words is "six hundred seventy-eight billion, eight hundred fifty-six million, six hundred eighty-six thousand, five hundred twenty-two".