66963781 has 2 divisors, whose sum is σ = 66963782. Its totient is φ = 66963780.

The previous prime is 66963779. The next prime is 66963791. The reversal of 66963781 is 18736966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43441281 + 23522500 = 6591^2 + 4850^2 .

It is a cyclic number.

It is not a de Polignac number, because 66963781 - 2¹ = 66963779 is a prime.

It is a super-2 number, since 2×66963781² = 8968295931631922, which contains 22 as substring.

Together with 66963779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66963791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33481890 + 33481891.

It is an arithmetic number, because the mean of its divisors is an integer number (33481891).

Almost surely, 2^66963781 is an apocalyptic number.

It is an amenable number.

66963781 is a deficient number, since it is larger than the sum of its proper divisors (1).

66963781 is an equidigital number, since it uses as much as digits as its factorization.

66963781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 46.

The square root of 66963781 is about 8183.1400452394. The cubic root of 66963781 is about 406.0816101808.

The spelling of 66963781 in words is "sixty-six million, nine hundred sixty-three thousand, seven hundred eighty-one".