665026 has 4 divisors (see below), whose sum is σ = 997542. Its totient is φ = 332512.

The previous prime is 665017. The next prime is 665029. The reversal of 665026 is 620566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 620566 = 2 ⋅310283.

It can be written as a sum of positive squares in only one way, i.e., 416025 + 249001 = 645^2 + 499^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665029) by changing a digit.

665026 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 as a sum of consecutive naturals, namely, 166255 + ... + 166258.

2⁶⁶⁵⁰²⁶ is an apocalyptic number.

665026 is a deficient number, since it is larger than the sum of its proper divisors (332516).

665026 is a wasteful number, since it uses less digits than its factorization.

665026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332515.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 665026 is about 815.4912629820. The cubic root of 665026 is about 87.2863248883.

The spelling of 665026 in words is "six hundred sixty-five thousand, twenty-six".