66405601 has 2 divisors, whose sum is σ = 66405602. Its totient is φ = 66405600.

The previous prime is 66405539. The next prime is 66405611. The reversal of 66405601 is 10650466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64000000 + 2405601 = 8000^2 + 1551^2 .

It is a cyclic number.

It is not a de Polignac number, because 66405601 - 2⁷ = 66405473 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66405601.

It is not a weakly prime, because it can be changed into another prime (66405611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33202800 + 33202801.

It is an arithmetic number, because the mean of its divisors is an integer number (33202801).

Almost surely, 2^66405601 is an apocalyptic number.

It is an amenable number.

66405601 is a deficient number, since it is larger than the sum of its proper divisors (1).

66405601 is an equidigital number, since it uses as much as digits as its factorization.

66405601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 66405601 is about 8148.9631855838. The cubic root of 66405601 is about 404.9501559346.

The spelling of 66405601 in words is "sixty-six million, four hundred five thousand, six hundred one".