667521111443209 has 2 divisors, whose sum is σ = 667521111443210. Its totient is φ = 667521111443208.

The previous prime is 667521111443089. The next prime is 667521111443231. The reversal of 667521111443209 is 902344111125766.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 643944065858809 + 23577045584400 = 25376053^2 + 4855620^2 .

It is a cyclic number.

It is not a de Polignac number, because 667521111443209 - 2⁴⁷ = 526783623087881 is a prime.

It is not a weakly prime, because it can be changed into another prime (667521111413209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333760555721604 + 333760555721605.

It is an arithmetic number, because the mean of its divisors is an integer number (333760555721605).

Almost surely, 2^{667521111443209} is an apocalyptic number.

It is an amenable number.

667521111443209 is a deficient number, since it is larger than the sum of its proper divisors (1).

667521111443209 is an equidigital number, since it uses as much as digits as its factorization.

667521111443209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2177280, while the sum is 52.

The spelling of 667521111443209 in words is "six hundred sixty-seven trillion, five hundred twenty-one billion, one hundred eleven million, four hundred forty-three thousand, two hundred nine".