1205540117 has 4 divisors (see below), whose sum is σ = 1205609580. Its totient is φ = 1205470656.

The previous prime is 1205540111. The next prime is 1205540123. The reversal of 1205540117 is 7110455021.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7110455021 = 3637 ⋅1955033.

It is an interprime number because it is at equal distance from previous prime (1205540111) and next prime (1205540123).

It can be written as a sum of positive squares in 2 ways, for example, as 1073152081 + 132388036 = 32759^2 + 11506^2 .

It is a cyclic number.

It is not a de Polignac number, because 1205540117 - 2⁶ = 1205540053 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 (1205540111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16109 + ... + 51677.

It is an arithmetic number, because the mean of its divisors is an integer number (301402395).

Almost surely, 2^1205540117 is an apocalyptic number.

It is an amenable number.

1205540117 is a deficient number, since it is larger than the sum of its proper divisors (69463).

1205540117 is an equidigital number, since it uses as much as digits as its factorization.

1205540117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69462.

The product of its (nonzero) digits is 1400, while the sum is 26.

The square root of 1205540117 is about 34720.8887703066. Note that the first 3 decimals coincide. The cubic root of 1205540117 is about 1064.2914069469.

Adding to 1205540117 its reverse (7110455021), we get a palindrome (8315995138).

The spelling of 1205540117 in words is "one billion, two hundred five million, five hundred forty thousand, one hundred seventeen".