686106728 has 8 divisors (see below), whose sum is σ = 1286450130. Its totient is φ = 343053360.

The previous prime is 686106727. The next prime is 686106731. The reversal of 686106728 is 827601686.

It can be written as a sum of positive squares in only one way, i.e., 477072964 + 209033764 = 21842^2 + 14458^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (686106727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42881663 + ... + 42881678.

Almost surely, 2^686106728 is an apocalyptic number.

It is an amenable number.

686106728 is a deficient number, since it is larger than the sum of its proper divisors (600343402).

686106728 is a wasteful number, since it uses less digits than its factorization.

686106728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85763347 (or 85763343 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 44.

The square root of 686106728 is about 26193.6390751648. The cubic root of 686106728 is about 881.9904702600.

The spelling of 686106728 in words is "six hundred eighty-six million, one hundred six thousand, seven hundred twenty-eight".