660409 has 2 divisors, whose sum is σ = 660410. Its totient is φ = 660408.

The previous prime is 660403. The next prime is 660449. The reversal of 660409 is 904066.

660409 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 558009 + 102400 = 747^2 + 320^2 .

It is a cyclic number.

It is not a de Polignac number, because 660409 - 2⁵ = 660377 is a prime.

It is a super-2 number, since 2×660409² = 872280094562, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (660403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330204 + 330205.

It is an arithmetic number, because the mean of its divisors is an integer number (330205).

2⁶⁶⁰⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

660409 is a deficient number, since it is larger than the sum of its proper divisors (1).

660409 is an equidigital number, since it uses as much as digits as its factorization.

660409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 660409 is about 812.6555235769. The cubic root of 660409 is about 87.0838580180.

It can be divided in two parts, 66040 and 9, that added together give a square (66049 = 257²).

The spelling of 660409 in words is "six hundred sixty thousand, four hundred nine".