66875561 has 2 divisors, whose sum is σ = 66875562. Its totient is φ = 66875560.

The previous prime is 66875503. The next prime is 66875609. The reversal of 66875561 is 16557866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53509225 + 13366336 = 7315^2 + 3656^2 .

It is a cyclic number.

It is not a de Polignac number, because 66875561 - 2¹⁰ = 66874537 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66875461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33437780 + 33437781.

It is an arithmetic number, because the mean of its divisors is an integer number (33437781).

Almost surely, 2^66875561 is an apocalyptic number.

It is an amenable number.

66875561 is a deficient number, since it is larger than the sum of its proper divisors (1).

66875561 is an equidigital number, since it uses as much as digits as its factorization.

66875561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 302400, while the sum is 44.

The square root of 66875561 is about 8177.7479173670. The cubic root of 66875561 is about 405.9032039702.

The spelling of 66875561 in words is "sixty-six million, eight hundred seventy-five thousand, five hundred sixty-one".