666123547 has 2 divisors, whose sum is σ = 666123548. Its totient is φ = 666123546.

The previous prime is 666123517. The next prime is 666123551. The reversal of 666123547 is 745321666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666123547 - 2²³ = 657734939 is a prime.

It is a super-2 number, since 2×666123547² = 887441159735722418, which contains 22 as substring.

It is equal to p_34587715 and since 666123547 and 34587715 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (666123517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333061773 + 333061774.

It is an arithmetic number, because the mean of its divisors is an integer number (333061774).

Almost surely, 2^666123547 is an apocalyptic number.

666123547 is a deficient number, since it is larger than the sum of its proper divisors (1).

666123547 is an equidigital number, since it uses as much as digits as its factorization.

666123547 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 40.

The square root of 666123547 is about 25809.3693646319. The cubic root of 666123547 is about 873.3431709198.

The spelling of 666123547 in words is "six hundred sixty-six million, one hundred twenty-three thousand, five hundred forty-seven".