1661443211 has 2 divisors, whose sum is σ = 1661443212. Its totient is φ = 1661443210.

The previous prime is 1661443193. The next prime is 1661443213. The reversal of 1661443211 is 1123441661.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661443211 is a prime.

It is a super-4 number, since 4×1661443211⁴ (a number of 38 digits) contains 4444 as substring.

Together with 1661443213, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1661443213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830721605 + 830721606.

It is an arithmetic number, because the mean of its divisors is an integer number (830721606).

Almost surely, 2^1661443211 is an apocalyptic number.

1661443211 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661443211 is an equidigital number, since it uses as much as digits as its factorization.

1661443211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 29.

The square root of 1661443211 is about 40760.8048374906. The cubic root of 1661443211 is about 1184.3911869663.

Adding to 1661443211 its reverse (1123441661), we get a palindrome (2784884872).

The spelling of 1661443211 in words is "one billion, six hundred sixty-one million, four hundred forty-three thousand, two hundred eleven".