321660 has 36 divisors (see below), whose sum is σ = 976248. Its totient is φ = 85728.

The previous prime is 321647. The next prime is 321661. The reversal of 321660 is 66123.

It is a happy number.

321660 is a `hidden beast` number, since 3 + 2 + 1 + 660 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (321661) by changing a digit.

321660 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 714 + ... + 1073.

It is an arithmetic number, because the mean of its divisors is an integer number (27118).

2³²¹⁶⁶⁰ is an apocalyptic number.

321660 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

321660 is an abundant number, since it is smaller than the sum of its proper divisors (654588).

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

321660 is a wasteful number, since it uses less digits than its factorization.

321660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1802 (or 1797 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 321660 is about 567.1507736043. The cubic root of 321660 is about 68.5171072764.

Adding to 321660 its reverse (66123), we get a palindrome (387783).

It can be divided in two parts, 3 and 21660, that multiplied together give a triangular number (64980 = T₃₆₀).

The spelling of 321660 in words is "three hundred twenty-one thousand, six hundred sixty".