661648 has 20 divisors (see below), whose sum is σ = 1380988. Its totient is φ = 305280.

The previous prime is 661621. The next prime is 661663. The reversal of 661648 is 846166.

It can be written as a sum of positive squares in 2 ways, for example, as 71824 + 589824 = 268^2 + 768^2 .

It is an unprimeable number.

661648 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 3 ways as a sum of consecutive naturals, for example, 1383 + ... + 1798.

2⁶⁶¹⁶⁴⁸ is an apocalyptic number.

It is an amenable number.

661648 is an abundant number, since it is smaller than the sum of its proper divisors (719340).

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

661648 is a wasteful number, since it uses less digits than its factorization.

661648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3202 (or 3196 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 661648 is about 813.4174819857. The cubic root of 661648 is about 87.1382836314.

The spelling of 661648 in words is "six hundred sixty-one thousand, six hundred forty-eight".