661328 has 10 divisors (see below), whose sum is σ = 1281354. Its totient is φ = 330656.

The previous prime is 661327. The next prime is 661343. The reversal of 661328 is 823166.

It can be written as a sum of positive squares in only one way, i.e., 652864 + 8464 = 808^2 + 92^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661297 and 661306.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20651 + ... + 20682.

2⁶⁶¹³²⁸ is an apocalyptic number.

It is an amenable number.

661328 is a deficient number, since it is larger than the sum of its proper divisors (620026).

661328 is a wasteful number, since it uses less digits than its factorization.

661328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41341 (or 41335 counting only the distinct ones).

The product of its digits is 1728, while the sum is 26.

The square root of 661328 is about 813.2207572363. The cubic root of 661328 is about 87.1242334883.

It can be divided in two parts, 661 and 328, that added together give a palindrome (989).

The spelling of 661328 in words is "six hundred sixty-one thousand, three hundred twenty-eight".