66789661 has 2 divisors, whose sum is σ = 66789662. Its totient is φ = 66789660.

The previous prime is 66789649. The next prime is 66789673. The reversal of 66789661 is 16698766.

It is a balanced prime because it is at equal distance from previous prime (66789649) and next prime (66789673).

It can be written as a sum of positive squares in only one way, i.e., 63920025 + 2869636 = 7995^2 + 1694^2 .

It is a cyclic number.

It is not a de Polignac number, because 66789661 - 2¹¹ = 66787613 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66789601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33394830 + 33394831.

It is an arithmetic number, because the mean of its divisors is an integer number (33394831).

Almost surely, 2^66789661 is an apocalyptic number.

It is an amenable number.

66789661 is a deficient number, since it is larger than the sum of its proper divisors (1).

66789661 is an equidigital number, since it uses as much as digits as its factorization.

66789661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 653184, while the sum is 49.

The square root of 66789661 is about 8172.4941725277. The cubic root of 66789661 is about 405.7293386398.

The spelling of 66789661 in words is "sixty-six million, seven hundred eighty-nine thousand, six hundred sixty-one".