665401 has 8 divisors (see below), whose sum is σ = 731808. Its totient is φ = 600000.

The previous prime is 665387. The next prime is 665419. The reversal of 665401 is 104566.

665401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 3-Lehmer number, since φ(665401) divides (665401-1)³.

It is a cyclic number.

It is not a de Polignac number, because 665401 - 2⁵ = 665369 is a prime.

It is a deceptive number, since it divides R₆₆₅₄₀₀.

It is not an unprimeable number, because it can be changed into a prime (665201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2526 + ... + 2776.

It is an arithmetic number, because the mean of its divisors is an integer number (91476).

It is a Poulet number, since it divides 2⁶⁶⁵⁴⁰⁰-1.

2⁶⁶⁵⁴⁰¹ is an apocalyptic number.

It is an amenable number.

665401 is a deficient number, since it is larger than the sum of its proper divisors (66407).

665401 is a wasteful number, since it uses less digits than its factorization.

665401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 665401 is about 815.7211533361. The cubic root of 665401 is about 87.3027283680.

Adding to 665401 its reverse (104566), we get a palindrome (769967).

The spelling of 665401 in words is "six hundred sixty-five thousand, four hundred one".