655980 has 72 divisors (see below), whose sum is σ = 2048592. Its totient is φ = 155904.

The previous prime is 655961. The next prime is 655987. The reversal of 655980 is 89556.

It is not an unprimeable number, because it can be changed into a prime (655987) by changing a digit.

655980 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22606 + ... + 22634.

2⁶⁵⁵⁹⁸⁰ is an apocalyptic number.

655980 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 655980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1024296).

655980 is an abundant number, since it is smaller than the sum of its proper divisors (1392612).

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

655980 is a wasteful number, since it uses less digits than its factorization.

655980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 52 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 33.

The square root of 655980 is about 809.9259225386. The cubic root of 655980 is about 86.8887466817. Note that the first 3 decimals are identical.

The spelling of 655980 in words is "six hundred fifty-five thousand, nine hundred eighty".