1205161311 has 4 divisors (see below), whose sum is σ = 1606881752. Its totient is φ = 803440872.

The previous prime is 1205161273. The next prime is 1205161333. The reversal of 1205161311 is 1131615021.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1131615021 = 3 ⋅377205007.

It is not a de Polignac number, because 1205161311 - 2⁷ = 1205161183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1205162311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200860216 + ... + 200860221.

It is an arithmetic number, because the mean of its divisors is an integer number (401720438).

Almost surely, 2^1205161311 is an apocalyptic number.

1205161311 is a deficient number, since it is larger than the sum of its proper divisors (401720441).

1205161311 is an equidigital number, since it uses as much as digits as its factorization.

1205161311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401720440.

The product of its (nonzero) digits is 180, while the sum is 21.

The square root of 1205161311 is about 34715.4333258279. The cubic root of 1205161311 is about 1064.1799210385.

Adding to 1205161311 its reverse (1131615021), we get a palindrome (2336776332).

The spelling of 1205161311 in words is "one billion, two hundred five million, one hundred sixty-one thousand, three hundred eleven".