66690649 has 2 divisors, whose sum is σ = 66690650. Its totient is φ = 66690648.

The previous prime is 66690623. The next prime is 66690653. The reversal of 66690649 is 94609666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66504025 + 186624 = 8155^2 + 432^2 .

It is a cyclic number.

It is not a de Polignac number, because 66690649 - 2²⁵ = 33136217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66690599 and 66690608.

It is not a weakly prime, because it can be changed into another prime (66696649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33345324 + 33345325.

It is an arithmetic number, because the mean of its divisors is an integer number (33345325).

Almost surely, 2^66690649 is an apocalyptic number.

It is an amenable number.

66690649 is a deficient number, since it is larger than the sum of its proper divisors (1).

66690649 is an equidigital number, since it uses as much as digits as its factorization.

66690649 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 419904, while the sum is 46.

The square root of 66690649 is about 8166.4342892109. The cubic root of 66690649 is about 405.5287490076.

The spelling of 66690649 in words is "sixty-six million, six hundred ninety thousand, six hundred forty-nine".