1221311213 has 2 divisors, whose sum is σ = 1221311214. Its totient is φ = 1221311212.

The previous prime is 1221311209. The next prime is 1221311233. The reversal of 1221311213 is 3121131221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 816416329 + 404894884 = 28573^2 + 20122^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221311213 - 2² = 1221311209 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1221311191 and 1221311200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221311233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610655606 + 610655607.

It is an arithmetic number, because the mean of its divisors is an integer number (610655607).

Almost surely, 2^1221311213 is an apocalyptic number.

It is an amenable number.

1221311213 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221311213 is an equidigital number, since it uses as much as digits as its factorization.

1221311213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 17.

The square root of 1221311213 is about 34947.2633120249. The cubic root of 1221311213 is about 1068.9123991195.

Adding to 1221311213 its reverse (3121131221), we get a palindrome (4342442434).

The spelling of 1221311213 in words is "one billion, two hundred twenty-one million, three hundred eleven thousand, two hundred thirteen".