66999997 has 2 divisors, whose sum is σ = 66999998.
Its totient is φ = 66999996.
The previous prime is 66999983. The next prime is 67000019. The reversal of 66999997 is 79999966.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 36650916 + 30349081 = 6054^2 + 5509^2
It is a cyclic number.
It is not a de Polignac number, because 66999997 - 211 = 66997949 is a prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (66999497) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (19) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33499998 + 33499999.
It is an arithmetic number, because the mean of its divisors is an integer number (33499999).
Almost surely, 266999997 is an apocalyptic number.
It is an amenable number.
66999997 is a deficient number, since it is larger than the sum of its proper divisors (1).
66999997 is an equidigital number, since it uses as much as digits as its factorization.
66999997 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 14880348, while the sum is 64.
The square root of 66999997 is about 8185.3525886183.
The cubic root of 66999997 is about 406.1548039826.
The spelling of 66999997 in words is "sixty-six million, nine hundred ninety-nine thousand, nine hundred ninety-seven".