1213315561 has 2 divisors, whose sum is σ = 1213315562. Its totient is φ = 1213315560.

The previous prime is 1213315511. The next prime is 1213315567. The reversal of 1213315561 is 1655133121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 894907225 + 318408336 = 29915^2 + 17844^2 .

It is a cyclic number.

It is not a de Polignac number, because 1213315561 - 2¹⁵ = 1213282793 is a prime.

It is not a weakly prime, because it can be changed into another prime (1213315567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606657780 + 606657781.

It is an arithmetic number, because the mean of its divisors is an integer number (606657781).

Almost surely, 2^1213315561 is an apocalyptic number.

It is an amenable number.

1213315561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213315561 is an equidigital number, since it uses as much as digits as its factorization.

1213315561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2700, while the sum is 28.

The square root of 1213315561 is about 34832.6794978509. The cubic root of 1213315561 is about 1066.5746464346.

Adding to 1213315561 its reverse (1655133121), we get a palindrome (2868448682).

The spelling of 1213315561 in words is "one billion, two hundred thirteen million, three hundred fifteen thousand, five hundred sixty-one".