1211728165 has 8 divisors (see below), whose sum is σ = 1475776800. Its totient is φ = 954913872.

The previous prime is 1211728139. The next prime is 1211728183. The reversal of 1211728165 is 5618271121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211728165 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1211728165.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1808215 + ... + 1808884.

It is an arithmetic number, because the mean of its divisors is an integer number (184472100).

Almost surely, 2^1211728165 is an apocalyptic number.

It is an amenable number.

1211728165 is a deficient number, since it is larger than the sum of its proper divisors (264048635).

1211728165 is an equidigital number, since it uses as much as digits as its factorization.

1211728165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3617171.

The product of its digits is 6720, while the sum is 34.

The square root of 1211728165 is about 34809.8860239444. The cubic root of 1211728165 is about 1066.1093057662.

Adding to 1211728165 its reverse (5618271121), we get a palindrome (6829999286).

The spelling of 1211728165 in words is "one billion, two hundred eleven million, seven hundred twenty-eight thousand, one hundred sixty-five".