685719720 has 144 divisors (see below), whose sum is σ = 2592507060. Its totient is φ = 156731904.

The previous prime is 685719691. The next prime is 685719731. The reversal of 685719720 is 27917586.

685719720 is a `hidden beast` number, since 6 + 8 + 571 + 9 + 72 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 632924964 + 52794756 = 25158^2 + 7266^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1797 + ... + 37076.

Almost surely, 2^685719720 is an apocalyptic number.

685719720 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 685719720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1296253530).

685719720 is an abundant number, since it is smaller than the sum of its proper divisors (1906787340).

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

685719720 is a wasteful number, since it uses less digits than its factorization.

685719720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38904 (or 38890 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The square root of 685719720 is about 26186.2505907203. The cubic root of 685719720 is about 881.8246060911.

The spelling of 685719720 in words is "six hundred eighty-five million, seven hundred nineteen thousand, seven hundred twenty".