665520 has 80 divisors (see below), whose sum is σ = 2142720. Its totient is φ = 170752.

The previous prime is 665507. The next prime is 665527. The reversal of 665520 is 25566.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (665527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11251 + ... + 11309.

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

2⁶⁶⁵⁵²⁰ is an apocalyptic number.

665520 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 665520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1071360).

665520 is an abundant number, since it is smaller than the sum of its proper divisors (1477200).

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

665520 is a wasteful number, since it uses less digits than its factorization.

665520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 665520 is about 815.7940916677. The cubic root of 665520 is about 87.3079324506.

665520 divided by its sum of digits (24) gives a triangular number (27730 = T₂₃₅).

The spelling of 665520 in words is "six hundred sixty-five thousand, five hundred twenty".