1561142163181 has 2 divisors, whose sum is σ = 1561142163182. Its totient is φ = 1561142163180.

The previous prime is 1561142163179. The next prime is 1561142163211. The reversal of 1561142163181 is 1813612411651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 930904647556 + 630237515625 = 964834^2 + 793875^2 .

It is an emirp because it is prime and its reverse (1813612411651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1561142163181 - 2¹ = 1561142163179 is a prime.

It is a super-2 number, since 2×1561142163181² (a number of 25 digits) contains 22 as substring.

Together with 1561142163179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561142163481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780571081590 + 780571081591.

It is an arithmetic number, because the mean of its divisors is an integer number (780571081591).

Almost surely, 2^{1561142163181} is an apocalyptic number.

It is an amenable number.

1561142163181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561142163181 is an equidigital number, since it uses as much as digits as its factorization.

1561142163181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 40.

The spelling of 1561142163181 in words is "one trillion, five hundred sixty-one billion, one hundred forty-two million, one hundred sixty-three thousand, one hundred eighty-one".