66405841 has 2 divisors, whose sum is σ = 66405842. Its totient is φ = 66405840.

The previous prime is 66405839. The next prime is 66405869. The reversal of 66405841 is 14850466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65674816 + 731025 = 8104^2 + 855^2 .

It is a cyclic number.

It is not a de Polignac number, because 66405841 - 2¹ = 66405839 is a prime.

Together with 66405839, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 66405797 and 66405806.

It is not a weakly prime, because it can be changed into another prime (66405821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33202920 + 33202921.

It is an arithmetic number, because the mean of its divisors is an integer number (33202921).

Almost surely, 2^66405841 is an apocalyptic number.

It is an amenable number.

66405841 is a deficient number, since it is larger than the sum of its proper divisors (1).

66405841 is an equidigital number, since it uses as much as digits as its factorization.

66405841 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 66405841 is about 8148.9779113702. The cubic root of 66405841 is about 404.9506437847.

The spelling of 66405841 in words is "sixty-six million, four hundred five thousand, eight hundred forty-one".