1213165817 has 4 divisors (see below), whose sum is σ = 1213699956. Its totient is φ = 1212631680.

The previous prime is 1213165799. The next prime is 1213165819. The reversal of 1213165817 is 7185613121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7185613121 = 7489 ⋅959489.

It can be written as a sum of positive squares in 2 ways, for example, as 412049401 + 801116416 = 20299^2 + 28304^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213165817 - 2⁶ = 1213165753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1213165819) 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, 263648 + ... + 268209.

It is an arithmetic number, because the mean of its divisors is an integer number (303424989).

Almost surely, 2^1213165817 is an apocalyptic number.

It is an amenable number.

1213165817 is a deficient number, since it is larger than the sum of its proper divisors (534139).

1213165817 is an equidigital number, since it uses as much as digits as its factorization.

1213165817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534138.

The product of its digits is 10080, while the sum is 35.

The square root of 1213165817 is about 34830.5299557730. The cubic root of 1213165817 is about 1066.5307667466.

Adding to 1213165817 its reverse (7185613121), we get a palindrome (8398778938).

The spelling of 1213165817 in words is "one billion, two hundred thirteen million, one hundred sixty-five thousand, eight hundred seventeen".