686102640 has 80 divisors (see below), whose sum is σ = 2132676000. Its totient is φ = 182465536.

The previous prime is 686102617. The next prime is 686102657. The reversal of 686102640 is 46201686.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×686102640² = 941473665229939200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 89686 + ... + 97034.

It is an arithmetic number, because the mean of its divisors is an integer number (26658450).

Almost surely, 2^686102640 is an apocalyptic number.

686102640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 686102640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1066338000).

686102640 is an abundant number, since it is smaller than the sum of its proper divisors (1446573360).

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

686102640 is a wasteful number, since it uses less digits than its factorization.

686102640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7754 (or 7748 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 33.

The square root of 686102640 is about 26193.5610408360. The cubic root of 686102640 is about 881.9887185480.

The spelling of 686102640 in words is "six hundred eighty-six million, one hundred two thousand, six hundred forty".