1665230221 has 2 divisors, whose sum is σ = 1665230222. Its totient is φ = 1665230220.

The previous prime is 1665230213. The next prime is 1665230233. The reversal of 1665230221 is 1220325661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1224020196 + 441210025 = 34986^2 + 21005^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665230221 - 2³ = 1665230213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1665230221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1665230201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832615110 + 832615111.

It is an arithmetic number, because the mean of its divisors is an integer number (832615111).

Almost surely, 2^1665230221 is an apocalyptic number.

It is an amenable number.

1665230221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665230221 is an equidigital number, since it uses as much as digits as its factorization.

1665230221 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 1665230221 is about 40807.2324594550. The cubic root of 1665230221 is about 1185.2903846621.

Adding to 1665230221 its reverse (1220325661), we get a palindrome (2885555882).

The spelling of 1665230221 in words is "one billion, six hundred sixty-five million, two hundred thirty thousand, two hundred twenty-one".