1221132145561 has 2 divisors, whose sum is σ = 1221132145562. Its totient is φ = 1221132145560.

The previous prime is 1221132145553. The next prime is 1221132145589. The reversal of 1221132145561 is 1655412311221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 888364685961 + 332767459600 = 942531^2 + 576860^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221132145561 - 2³ = 1221132145553 is a prime.

It is a super-2 number, since 2×1221132145561² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1221132145061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610566072780 + 610566072781.

It is an arithmetic number, because the mean of its divisors is an integer number (610566072781).

Almost surely, 2^{1221132145561} is an apocalyptic number.

It is an amenable number.

1221132145561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221132145561 is an equidigital number, since it uses as much as digits as its factorization.

1221132145561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14400, while the sum is 34.

Adding to 1221132145561 its reverse (1655412311221), we get a palindrome (2876544456782).

The spelling of 1221132145561 in words is "one trillion, two hundred twenty-one billion, one hundred thirty-two million, one hundred forty-five thousand, five hundred sixty-one".