686213640 has 192 divisors, whose sum is σ = 2661033600. Its totient is φ = 156836736.

The previous prime is 686213629. The next prime is 686213657. The reversal of 686213640 is 46312686.

686213640 is a `hidden beast` number, since 6 + 8 + 6 + 2 + 1 + 3 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 686213595 and 686213604.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 46437 + ... + 59403.

It is an arithmetic number, because the mean of its divisors is an integer number (13859550).

Almost surely, 2^686213640 is an apocalyptic number.

686213640 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 686213640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1330516800).

686213640 is an abundant number, since it is smaller than the sum of its proper divisors (1974819960).

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

686213640 is a wasteful number, since it uses less digits than its factorization.

686213640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13001 (or 12984 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 686213640 is about 26195.6797964855. The cubic root of 686213640 is about 882.0362796868.

It can be divided in two parts, 6862 and 13640, that added together give a palindrome (20502).

The spelling of 686213640 in words is "six hundred eighty-six million, two hundred thirteen thousand, six hundred forty".