66691699 has 2 divisors, whose sum is σ = 66691700. Its totient is φ = 66691698.

The previous prime is 66691693. The next prime is 66691711. The reversal of 66691699 is 99619666.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66691699 is a prime.

It is not a weakly prime, because it can be changed into another prime (66691693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33345849 + 33345850.

It is an arithmetic number, because the mean of its divisors is an integer number (33345850).

Almost surely, 2^66691699 is an apocalyptic number.

66691699 is a deficient number, since it is larger than the sum of its proper divisors (1).

66691699 is an equidigital number, since it uses as much as digits as its factorization.

66691699 is an evil number, because the sum of its binary digits is even.

The product of its digits is 944784, while the sum is 52.

The square root of 66691699 is about 8166.4985765014. The cubic root of 66691699 is about 405.5308772568.

The spelling of 66691699 in words is "sixty-six million, six hundred ninety-one thousand, six hundred ninety-nine".