665590 has 16 divisors (see below), whose sum is σ = 1211760. Its totient is φ = 263200.

The previous prime is 665573. The next prime is 665591. The reversal of 665590 is 95566.

It is a happy number.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665591) by changing a digit.

665590 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 7 ways as a sum of consecutive naturals, for example, 681 + ... + 1339.

It is an arithmetic number, because the mean of its divisors is an integer number (75735).

2⁶⁶⁵⁵⁹⁰ is an apocalyptic number.

665590 is a deficient number, since it is larger than the sum of its proper divisors (546170).

665590 is a wasteful number, since it uses less digits than its factorization.

665590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 767.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 665590 is about 815.8369935226. The cubic root of 665590 is about 87.3109933859.

The spelling of 665590 in words is "six hundred sixty-five thousand, five hundred ninety".