1561110505111 has 4 divisors (see below), whose sum is σ = 1561165527352. Its totient is φ = 1561055482872.

The previous prime is 1561110505091. The next prime is 1561110505127. The reversal of 1561110505111 is 1115050111651.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1561110505111 - 2⁵ = 1561110505079 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561110505111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561110535111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27468540 + ... + 27525313.

It is an arithmetic number, because the mean of its divisors is an integer number (390291381838).

Almost surely, 2^{1561110505111} is an apocalyptic number.

1561110505111 is a deficient number, since it is larger than the sum of its proper divisors (55022241).

1561110505111 is an equidigital number, since it uses as much as digits as its factorization.

1561110505111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55022240.

The product of its (nonzero) digits is 750, while the sum is 28.

Adding to 1561110505111 its reverse (1115050111651), we get a palindrome (2676160616762).

The spelling of 1561110505111 in words is "one trillion, five hundred sixty-one billion, one hundred ten million, five hundred five thousand, one hundred eleven".