1665808201 has 2 divisors, whose sum is σ = 1665808202. Its totient is φ = 1665808200.

The previous prime is 1665808181. The next prime is 1665808213. The reversal of 1665808201 is 1028085661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1001406025 + 664402176 = 31645^2 + 25776^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665808201 - 2¹⁷ = 1665677129 is a prime.

It is not a weakly prime, because it can be changed into another prime (1665808231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832904100 + 832904101.

It is an arithmetic number, because the mean of its divisors is an integer number (832904101).

Almost surely, 2^1665808201 is an apocalyptic number.

It is an amenable number.

1665808201 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665808201 is an equidigital number, since it uses as much as digits as its factorization.

1665808201 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 37.

The square root of 1665808201 is about 40814.3136779243. The cubic root of 1665808201 is about 1185.4275018172.

The spelling of 1665808201 in words is "one billion, six hundred sixty-five million, eight hundred eight thousand, two hundred one".