66838817 has 2 divisors, whose sum is σ = 66838818. Its totient is φ = 66838816.

The previous prime is 66838769. The next prime is 66838843. The reversal of 66838817 is 71883866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62742241 + 4096576 = 7921^2 + 2024^2 .

It is a cyclic number.

It is not a de Polignac number, because 66838817 - 2¹⁴ = 66822433 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66838847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33419408 + 33419409.

It is an arithmetic number, because the mean of its divisors is an integer number (33419409).

Almost surely, 2^66838817 is an apocalyptic number.

It is an amenable number.

66838817 is a deficient number, since it is larger than the sum of its proper divisors (1).

66838817 is an equidigital number, since it uses as much as digits as its factorization.

66838817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 47.

The square root of 66838817 is about 8175.5010244021. The cubic root of 66838817 is about 405.8288507512.

The spelling of 66838817 in words is "sixty-six million, eight hundred thirty-eight thousand, eight hundred seventeen".