66898409 has 2 divisors, whose sum is σ = 66898410. Its totient is φ = 66898408.

The previous prime is 66898399. The next prime is 66898453. The reversal of 66898409 is 90489866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66504025 + 394384 = 8155^2 + 628^2 .

It is a cyclic number.

It is not a de Polignac number, because 66898409 - 2¹⁶ = 66832873 is a prime.

It is not a weakly prime, because it can be changed into another prime (66898459) 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, 33449204 + 33449205.

It is an arithmetic number, because the mean of its divisors is an integer number (33449205).

Almost surely, 2^66898409 is an apocalyptic number.

It is an amenable number.

66898409 is a deficient number, since it is larger than the sum of its proper divisors (1).

66898409 is an equidigital number, since it uses as much as digits as its factorization.

66898409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 746496, while the sum is 50.

The square root of 66898409 is about 8179.1447596922. The cubic root of 66898409 is about 405.9494242451.

The spelling of 66898409 in words is "sixty-six million, eight hundred ninety-eight thousand, four hundred nine".