66697909 has 2 divisors, whose sum is σ = 66697910. Its totient is φ = 66697908.

The previous prime is 66697889. The next prime is 66697937. The reversal of 66697909 is 90979666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65966884 + 731025 = 8122^2 + 855^2 .

It is a cyclic number.

It is not a de Polignac number, because 66697909 - 2¹³ = 66689717 is a prime.

It is a super-2 number, since 2×66697909² = 8897222129944562, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66697109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33348954 + 33348955.

It is an arithmetic number, because the mean of its divisors is an integer number (33348955).

Almost surely, 2^66697909 is an apocalyptic number.

It is an amenable number.

66697909 is a deficient number, since it is larger than the sum of its proper divisors (1).

66697909 is an equidigital number, since it uses as much as digits as its factorization.

66697909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1102248, while the sum is 52.

The square root of 66697909 is about 8166.8787795583. The cubic root of 66697909 is about 405.5434638736.

The spelling of 66697909 in words is "sixty-six million, six hundred ninety-seven thousand, nine hundred nine".