668539 has 2 divisors, whose sum is σ = 668540. Its totient is φ = 668538.

The previous prime is 668533. The next prime is 668543. The reversal of 668539 is 935866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 668539 - 2³ = 668531 is a prime.

668539 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 668498 and 668507.

It is not a weakly prime, because it can be changed into another prime (668531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334269 + 334270.

It is an arithmetic number, because the mean of its divisors is an integer number (334270).

2⁶⁶⁸⁵³⁹ is an apocalyptic number.

668539 is a deficient number, since it is larger than the sum of its proper divisors (1).

668539 is an equidigital number, since it uses as much as digits as its factorization.

668539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 37.

The square root of 668539 is about 817.6423423478. The cubic root of 668539 is about 87.4397517227.

It can be divided in two parts, 6685 and 39, that added together give a square (6724 = 82²).

The spelling of 668539 in words is "six hundred sixty-eight thousand, five hundred thirty-nine".