661580 has 24 divisors (see below), whose sum is σ = 1463280. Its totient is φ = 250560.

The previous prime is 661553. The next prime is 661603. The reversal of 661580 is 85166.

It is a congruent number.

It is an unprimeable number.

661580 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 491 + ... + 1250.

It is an arithmetic number, because the mean of its divisors is an integer number (60970).

2⁶⁶¹⁵⁸⁰ is an apocalyptic number.

It is an amenable number.

661580 is an abundant number, since it is smaller than the sum of its proper divisors (801700).

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

661580 is a wasteful number, since it uses less digits than its factorization.

661580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1769 (or 1767 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 661580 is about 813.3756819576. The cubic root of 661580 is about 87.1352983551.

The spelling of 661580 in words is "six hundred sixty-one thousand, five hundred eighty".