1213213817 has 4 divisors (see below), whose sum is σ = 1216814196. Its totient is φ = 1209613440.

The previous prime is 1213213763. The next prime is 1213213819. The reversal of 1213213817 is 7183123121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7183123121 = 347 ⋅20700643.

It can be written as a sum of positive squares in 2 ways, for example, as 116014441 + 1097199376 = 10771^2 + 33124^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213213817 - 2¹⁶ = 1213148281 is a prime.

It is a Duffinian number.

1213213817 is a modest number, since divided by 13817 gives 12132 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 1213213817.

It is not an unprimeable number, because it can be changed into a prime (1213213819) 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, 1799684 + ... + 1800357.

It is an arithmetic number, because the mean of its divisors is an integer number (304203549).

Almost surely, 2^1213213817 is an apocalyptic number.

It is an amenable number.

1213213817 is a deficient number, since it is larger than the sum of its proper divisors (3600379).

1213213817 is an equidigital number, since it uses as much as digits as its factorization.

1213213817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3600378.

The product of its digits is 2016, while the sum is 29.

The square root of 1213213817 is about 34831.2189996273. The cubic root of 1213213817 is about 1066.5448326451.

Adding to 1213213817 its reverse (7183123121), we get a palindrome (8396336938).

The spelling of 1213213817 in words is "one billion, two hundred thirteen million, two hundred thirteen thousand, eight hundred seventeen".