1212321221 has 4 divisors (see below), whose sum is σ = 1283634252. Its totient is φ = 1141008192.

The previous prime is 1212321193. The next prime is 1212321233. The reversal of 1212321221 is 1221232121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1221232121 = 43 ⋅28400747.

It can be written as a sum of positive squares in 2 ways, for example, as 1038450625 + 173870596 = 32225^2 + 13186^2 .

It is a cyclic number.

It is not a de Polignac number, because 1212321221 - 2¹⁴ = 1212304837 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 71313013 = 1212321221 / (1 + 2 + 1 + 2 + 3 + 2 + 1 + 2 + 2 + 1).

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1212321221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212329221) 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, 35656490 + ... + 35656523.

It is an arithmetic number, because the mean of its divisors is an integer number (320908563).

Almost surely, 2^1212321221 is an apocalyptic number.

It is an amenable number.

1212321221 is a deficient number, since it is larger than the sum of its proper divisors (71313031).

1212321221 is an equidigital number, since it uses as much as digits as its factorization.

1212321221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71313030.

The product of its digits is 96, while the sum is 17.

The square root of 1212321221 is about 34818.4034814924. The cubic root of 1212321221 is about 1066.2832059905.

Adding to 1212321221 its reverse (1221232121), we get a palindrome (2433553342).

The spelling of 1212321221 in words is "one billion, two hundred twelve million, three hundred twenty-one thousand, two hundred twenty-one".