66978851 has 2 divisors, whose sum is σ = 66978852. Its totient is φ = 66978850.

The previous prime is 66978841. The next prime is 66978881. The reversal of 66978851 is 15887966.

It is a happy number.

66978851 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66978851 - 2¹⁸ = 66716707 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66978851.

It is not a weakly prime, because it can be changed into another prime (66978811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33489425 + 33489426.

It is an arithmetic number, because the mean of its divisors is an integer number (33489426).

Almost surely, 2^66978851 is an apocalyptic number.

66978851 is a deficient number, since it is larger than the sum of its proper divisors (1).

66978851 is an equidigital number, since it uses as much as digits as its factorization.

66978851 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 50.

The square root of 66978851 is about 8184.0607891193. The cubic root of 66978851 is about 406.1120703827.

The spelling of 66978851 in words is "sixty-six million, nine hundred seventy-eight thousand, eight hundred fifty-one".