1491218321 has 2 divisors, whose sum is σ = 1491218322. Its totient is φ = 1491218320.

The previous prime is 1491218297. The next prime is 1491218353. The reversal of 1491218321 is 1238121941.

It is an a-pointer prime, because the next prime (1491218353) can be obtained adding 1491218321 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1284433921 + 206784400 = 35839^2 + 14380^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1491218321 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1491218621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 745609160 + 745609161.

It is an arithmetic number, because the mean of its divisors is an integer number (745609161).

Almost surely, 2^1491218321 is an apocalyptic number.

It is an amenable number.

1491218321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1491218321 is an equidigital number, since it uses as much as digits as its factorization.

1491218321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 32.

The square root of 1491218321 is about 38616.2960549041. The cubic root of 1491218321 is about 1142.4759771310.

It can be divided in two parts, 14912 and 18321, that added together give a palindrome (33233).

The spelling of 1491218321 in words is "one billion, four hundred ninety-one million, two hundred eighteen thousand, three hundred twenty-one".