66999697 has 2 divisors, whose sum is σ = 66999698. Its totient is φ = 66999696.

The previous prime is 66999689. The next prime is 66999701. The reversal of 66999697 is 79699966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34292736 + 32706961 = 5856^2 + 5719^2 .

It is a cyclic number.

It is not a de Polignac number, because 66999697 - 2³ = 66999689 is a prime.

It is not a weakly prime, because it can be changed into another prime (66999497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33499848 + 33499849.

It is an arithmetic number, because the mean of its divisors is an integer number (33499849).

Almost surely, 2^66999697 is an apocalyptic number.

It is an amenable number.

66999697 is a deficient number, since it is larger than the sum of its proper divisors (1).

66999697 is an equidigital number, since it uses as much as digits as its factorization.

66999697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9920232, while the sum is 61.

The square root of 66999697 is about 8185.3342631807. The cubic root of 66999697 is about 406.1541977804.

The spelling of 66999697 in words is "sixty-six million, nine hundred ninety-nine thousand, six hundred ninety-seven".