1205136857 has 4 divisors (see below), whose sum is σ = 1212103140. Its totient is φ = 1198170576.

The previous prime is 1205136853. The next prime is 1205136887. The reversal of 1205136857 is 7586315021.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7586315021 = 66347 ⋅114343.

It can be written as a sum of positive squares in 2 ways, for example, as 1030474201 + 174662656 = 32101^2 + 13216^2 .

It is a cyclic number.

It is not a de Polignac number, because 1205136857 - 2² = 1205136853 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1205136857.

It is not an unprimeable number, because it can be changed into a prime (1205136853) 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, 3482882 + ... + 3483227.

It is an arithmetic number, because the mean of its divisors is an integer number (303025785).

Almost surely, 2^1205136857 is an apocalyptic number.

It is an amenable number.

1205136857 is a deficient number, since it is larger than the sum of its proper divisors (6966283).

1205136857 is an equidigital number, since it uses as much as digits as its factorization.

1205136857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6966282.

The product of its (nonzero) digits is 50400, while the sum is 38.

The square root of 1205136857 is about 34715.0811175777. The cubic root of 1205136857 is about 1064.1727232104.

The spelling of 1205136857 in words is "one billion, two hundred five million, one hundred thirty-six thousand, eight hundred fifty-seven".