661080 has 64 divisors (see below), whose sum is σ = 2269440. Its totient is φ = 150912.

The previous prime is 661061. The next prime is 661091. The reversal of 661080 is 80166.

It is a Harshad number since it is a multiple of its sum of digits (21).

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 661080.

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, 447 + ... + 1233.

It is an arithmetic number, because the mean of its divisors is an integer number (35460).

2⁶⁶¹⁰⁸⁰ is an apocalyptic number.

661080 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1134720).

661080 is an abundant number, since it is smaller than the sum of its proper divisors (1608360).

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

661080 is a wasteful number, since it uses less digits than its factorization.

661080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 808 (or 804 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 661080 is about 813.0682628168. The cubic root of 661080 is about 87.1133415097.

The spelling of 661080 in words is "six hundred sixty-one thousand, eighty".