665081 has 4 divisors (see below), whose sum is σ = 680592. Its totient is φ = 649572.

The previous prime is 665069. The next prime is 665089. The reversal of 665081 is 180566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 665081 - 2⁶ = 665017 is a prime.

It is a super-2 number, since 2×665081² = 884665473122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 665081.

It is not an unprimeable number, because it can be changed into a prime (665089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7691 + ... + 7776.

It is an arithmetic number, because the mean of its divisors is an integer number (170148).

2⁶⁶⁵⁰⁸¹ is an apocalyptic number.

It is an amenable number.

665081 is a deficient number, since it is larger than the sum of its proper divisors (15511).

665081 is a wasteful number, since it uses less digits than its factorization.

665081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15510.

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

The square root of 665081 is about 815.5249842893. The cubic root of 665081 is about 87.2887311178.

The spelling of 665081 in words is "six hundred sixty-five thousand, eighty-one".