66778541 has 2 divisors, whose sum is σ = 66778542. Its totient is φ = 66778540.

The previous prime is 66778531. The next prime is 66778549. The reversal of 66778541 is 14587766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62173225 + 4605316 = 7885^2 + 2146^2 .

It is a cyclic number.

It is not a de Polignac number, because 66778541 - 2⁶ = 66778477 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 66778492 and 66778501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66778549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33389270 + 33389271.

It is an arithmetic number, because the mean of its divisors is an integer number (33389271).

Almost surely, 2^66778541 is an apocalyptic number.

It is an amenable number.

66778541 is a deficient number, since it is larger than the sum of its proper divisors (1).

66778541 is an equidigital number, since it uses as much as digits as its factorization.

66778541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 282240, while the sum is 44.

The square root of 66778541 is about 8171.8138133465. The cubic root of 66778541 is about 405.7068203808.

The spelling of 66778541 in words is "sixty-six million, seven hundred seventy-eight thousand, five hundred forty-one".