661584 has 80 divisors (see below), whose sum is σ = 2142720. Its totient is φ = 170880.

The previous prime is 661553. The next prime is 661603. The reversal of 661584 is 485166.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661584.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3607 + ... + 3785.

It is an arithmetic number, because the mean of its divisors is an integer number (26784).

2⁶⁶¹⁵⁸⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661584, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1071360).

661584 is an abundant number, since it is smaller than the sum of its proper divisors (1481136).

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

661584 is a wasteful number, since it uses less digits than its factorization.

661584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208 (or 202 counting only the distinct ones).

The product of its digits is 5760, while the sum is 30.

The square root of 661584 is about 813.3781408423. The cubic root of 661584 is about 87.1354739653.

The spelling of 661584 in words is "six hundred sixty-one thousand, five hundred eighty-four".