656820 has 72 divisors (see below), whose sum is σ = 2063880. Its totient is φ = 168960.

The previous prime is 656819. The next prime is 656833. The reversal of 656820 is 28656.

656820 is a `hidden beast` number, since 656 + 8 + 2 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 10404 + 646416 = 102^2 + 804^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7336 + ... + 7424.

It is an arithmetic number, because the mean of its divisors is an integer number (28665).

2⁶⁵⁶⁸²⁰ is an apocalyptic number.

656820 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 656820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1031940).

656820 is an abundant number, since it is smaller than the sum of its proper divisors (1407060).

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

656820 is a wasteful number, since it uses less digits than its factorization.

656820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 656820 is about 810.4443225787. Note that the first 3 decimals coincide. The cubic root of 656820 is about 86.9258186532.

The spelling of 656820 in words is "six hundred fifty-six thousand, eight hundred twenty".