665251 has 2 divisors, whose sum is σ = 665252. Its totient is φ = 665250.

The previous prime is 665239. The next prime is 665267. The reversal of 665251 is 152566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665251 - 2⁷ = 665123 is a prime.

It is not a weakly prime, because it can be changed into another prime (665201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332625 + 332626.

It is an arithmetic number, because the mean of its divisors is an integer number (332626).

2⁶⁶⁵²⁵¹ is an apocalyptic number.

665251 is a deficient number, since it is larger than the sum of its proper divisors (1).

665251 is an equidigital number, since it uses as much as digits as its factorization.

665251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1800, while the sum is 25.

The square root of 665251 is about 815.6292049700. The cubic root of 665251 is about 87.2961677159.

The spelling of 665251 in words is "six hundred sixty-five thousand, two hundred fifty-one".