685980 has 72 divisors (see below), whose sum is σ = 2157792. Its totient is φ = 176256.

The previous prime is 685973. The next prime is 685987. The reversal of 685980 is 89586.

685980 = 25² + 26² + ... + 127².

685980 is a `hidden beast` number, since 68 + 598 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (685973) and next prime (685987).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685987) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6609 + ... + 6711.

2⁶⁸⁵⁹⁸⁰ is an apocalyptic number.

685980 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 685980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1078896).

685980 is an abundant number, since it is smaller than the sum of its proper divisors (1471812).

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

685980 is a wasteful number, since it uses less digits than its factorization.

685980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 150 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 685980 is about 828.2390959137. The cubic root of 685980 is about 88.1936163952.

The spelling of 685980 in words is "six hundred eighty-five thousand, nine hundred eighty".