66605551 has 2 divisors, whose sum is σ = 66605552. Its totient is φ = 66605550.

The previous prime is 66605537. The next prime is 66605557. The reversal of 66605551 is 15550666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66605551 - 2¹¹ = 66603503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66605557) 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, 33302775 + 33302776.

It is an arithmetic number, because the mean of its divisors is an integer number (33302776).

Almost surely, 2^66605551 is an apocalyptic number.

66605551 is a deficient number, since it is larger than the sum of its proper divisors (1).

66605551 is an equidigital number, since it uses as much as digits as its factorization.

66605551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27000, while the sum is 34.

The square root of 66605551 is about 8161.2223961855. Note that the first 3 decimals coincide. The cubic root of 66605551 is about 405.3561892127.

The spelling of 66605551 in words is "sixty-six million, six hundred five thousand, five hundred fifty-one".