1221401243 has 2 divisors, whose sum is σ = 1221401244. Its totient is φ = 1221401242.

The previous prime is 1221401239. The next prime is 1221401257. The reversal of 1221401243 is 3421041221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221401243 - 2² = 1221401239 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221404243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610700621 + 610700622.

It is an arithmetic number, because the mean of its divisors is an integer number (610700622).

Almost surely, 2^1221401243 is an apocalyptic number.

1221401243 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221401243 is an equidigital number, since it uses as much as digits as its factorization.

1221401243 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 1221401243 is about 34948.5513719811. The cubic root of 1221401243 is about 1068.9386637378.

Adding to 1221401243 its reverse (3421041221), we get a palindrome (4642442464).

The spelling of 1221401243 in words is "one billion, two hundred twenty-one million, four hundred one thousand, two hundred forty-three".