66646819 has 2 divisors, whose sum is σ = 66646820. Its totient is φ = 66646818.

The previous prime is 66646787. The next prime is 66646829. The reversal of 66646819 is 91864666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66646819 - 2⁵ = 66646787 is a prime.

It is a super-2 number, since 2×66646819² = 8883596965637522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66646829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33323409 + 33323410.

It is an arithmetic number, because the mean of its divisors is an integer number (33323410).

Almost surely, 2^66646819 is an apocalyptic number.

66646819 is a deficient number, since it is larger than the sum of its proper divisors (1).

66646819 is an equidigital number, since it uses as much as digits as its factorization.

66646819 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 46.

The square root of 66646819 is about 8163.7503024039. The cubic root of 66646819 is about 405.4398898717.

The spelling of 66646819 in words is "sixty-six million, six hundred forty-six thousand, eight hundred nineteen".