66664919 has 2 divisors, whose sum is σ = 66664920. Its totient is φ = 66664918.

The previous prime is 66664909. The next prime is 66664951. The reversal of 66664919 is 91946666.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66664919 - 2²⁴ = 49887703 is a prime.

It is a super-2 number, since 2×66664919² = 8888422850553122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66664909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33332459 + 33332460.

It is an arithmetic number, because the mean of its divisors is an integer number (33332460).

Almost surely, 2^66664919 is an apocalyptic number.

66664919 is a deficient number, since it is larger than the sum of its proper divisors (1).

66664919 is an equidigital number, since it uses as much as digits as its factorization.

66664919 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 47.

The square root of 66664919 is about 8164.8587862865. The cubic root of 66664919 is about 405.4765897867.

The spelling of 66664919 in words is "sixty-six million, six hundred sixty-four thousand, nine hundred nineteen".