1221313421 has 2 divisors, whose sum is σ = 1221313422. Its totient is φ = 1221313420.

The previous prime is 1221313411. The next prime is 1221313441. The reversal of 1221313421 is 1243131221.

It is an a-pointer prime, because the next prime (1221313441) can be obtained adding 1221313421 to its sum of digits (20).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 980629225 + 240684196 = 31315^2 + 15514^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221313421 - 2¹⁸ = 1221051277 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221313393 and 1221313402.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221313411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610656710 + 610656711.

It is an arithmetic number, because the mean of its divisors is an integer number (610656711).

Almost surely, 2^1221313421 is an apocalyptic number.

It is an amenable number.

1221313421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221313421 is an equidigital number, since it uses as much as digits as its factorization.

1221313421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 20.

The square root of 1221313421 is about 34947.2949024671. The cubic root of 1221313421 is about 1068.9130432788.

Adding to 1221313421 its reverse (1243131221), we get a palindrome (2464444642).

The spelling of 1221313421 in words is "one billion, two hundred twenty-one million, three hundred thirteen thousand, four hundred twenty-one".