66199979 has 2 divisors, whose sum is σ = 66199980. Its totient is φ = 66199978.

The previous prime is 66199967. The next prime is 66199981. The reversal of 66199979 is 97999166.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66199979 is a prime.

It is a Sophie Germain prime.

Together with 66199981, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66199949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33099989 + 33099990.

It is an arithmetic number, because the mean of its divisors is an integer number (33099990).

Almost surely, 2^66199979 is an apocalyptic number.

66199979 is a deficient number, since it is larger than the sum of its proper divisors (1).

66199979 is an equidigital number, since it uses as much as digits as its factorization.

66199979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1653372, while the sum is 56.

The square root of 66199979 is about 8136.3369522163. The cubic root of 66199979 is about 404.5317537130.

The spelling of 66199979 in words is "sixty-six million, one hundred ninety-nine thousand, nine hundred seventy-nine".