66553391 has 2 divisors, whose sum is σ = 66553392. Its totient is φ = 66553390.

The previous prime is 66553387. The next prime is 66553423. The reversal of 66553391 is 19335566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66553391 - 2² = 66553387 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66553321) 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, 33276695 + 33276696.

It is an arithmetic number, because the mean of its divisors is an integer number (33276696).

Almost surely, 2^66553391 is an apocalyptic number.

66553391 is a deficient number, since it is larger than the sum of its proper divisors (1).

66553391 is an equidigital number, since it uses as much as digits as its factorization.

66553391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72900, while the sum is 38.

The square root of 66553391 is about 8158.0261705881. The cubic root of 66553391 is about 405.2503476816.

The spelling of 66553391 in words is "sixty-six million, five hundred fifty-three thousand, three hundred ninety-one".