1243561321 has 2 divisors, whose sum is σ = 1243561322. Its totient is φ = 1243561320.

The previous prime is 1243561303. The next prime is 1243561331. The reversal of 1243561321 is 1231653421.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1227521296 + 16040025 = 35036^2 + 4005^2 .

It is an emirp because it is prime and its reverse (1231653421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1243561321 - 2⁵ = 1243561289 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1243561321.

It is not a weakly prime, because it can be changed into another prime (1243561331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621780660 + 621780661.

It is an arithmetic number, because the mean of its divisors is an integer number (621780661).

Almost surely, 2^1243561321 is an apocalyptic number.

It is an amenable number.

1243561321 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243561321 is an equidigital number, since it uses as much as digits as its factorization.

1243561321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 28.

The square root of 1243561321 is about 35264.1648277681. The cubic root of 1243561321 is about 1075.3645984484.

The spelling of 1243561321 in words is "one billion, two hundred forty-three million, five hundred sixty-one thousand, three hundred twenty-one".