66822781 has 2 divisors, whose sum is σ = 66822782. Its totient is φ = 66822780.

The previous prime is 66822779. The next prime is 66822787. The reversal of 66822781 is 18722866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 36120100 + 30702681 = 6010^2 + 5541^2 .

It is a cyclic number.

It is not a de Polignac number, because 66822781 - 2¹ = 66822779 is a prime.

It is a super-2 number, since 2×66822781² = 8930568121147922, which contains 22 as substring.

Together with 66822779, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66822787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33411390 + 33411391.

It is an arithmetic number, because the mean of its divisors is an integer number (33411391).

Almost surely, 2^66822781 is an apocalyptic number.

It is an amenable number.

66822781 is a deficient number, since it is larger than the sum of its proper divisors (1).

66822781 is an equidigital number, since it uses as much as digits as its factorization.

66822781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 40.

The square root of 66822781 is about 8174.5202305701. The cubic root of 66822781 is about 405.7963926065.

The spelling of 66822781 in words is "sixty-six million, eight hundred twenty-two thousand, seven hundred eighty-one".