1561061270981 has 2 divisors, whose sum is σ = 1561061270982. Its totient is φ = 1561061270980.

The previous prime is 1561061270959. The next prime is 1561061271023. The reversal of 1561061270981 is 1890721601651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1398034288225 + 163026982756 = 1182385^2 + 403766^2 .

It is an emirp because it is prime and its reverse (1890721601651) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1561061270981 is a prime.

It is a super-2 number, since 2×1561061270981² (a number of 25 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561061270581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780530635490 + 780530635491.

It is an arithmetic number, because the mean of its divisors is an integer number (780530635491).

Almost surely, 2^{1561061270981} is an apocalyptic number.

It is an amenable number.

1561061270981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561061270981 is an equidigital number, since it uses as much as digits as its factorization.

1561061270981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 181440, while the sum is 47.

The spelling of 1561061270981 in words is "one trillion, five hundred sixty-one billion, sixty-one million, two hundred seventy thousand, nine hundred eighty-one".