1212166321 has 4 divisors (see below), whose sum is σ = 1212434944. Its totient is φ = 1211897700.

The previous prime is 1212166303. The next prime is 1212166343. The reversal of 1212166321 is 1236612121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1236612121 = 167 ⋅7404863.

It is a cyclic number.

It is not a de Polignac number, because 1212166321 - 2¹¹ = 1212164273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1212166301) 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, 127425 + ... + 136606.

It is an arithmetic number, because the mean of its divisors is an integer number (303108736).

Almost surely, 2^1212166321 is an apocalyptic number.

It is an amenable number.

1212166321 is a deficient number, since it is larger than the sum of its proper divisors (268623).

1212166321 is an equidigital number, since it uses as much as digits as its factorization.

1212166321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268622.

The product of its digits is 864, while the sum is 25.

The square root of 1212166321 is about 34816.1790120628. The cubic root of 1212166321 is about 1066.2377905509.

Adding to 1212166321 its reverse (1236612121), we get a palindrome (2448778442).

The spelling of 1212166321 in words is "one billion, two hundred twelve million, one hundred sixty-six thousand, three hundred twenty-one".