1561655656111 has 4 divisors (see below), whose sum is σ = 1570682567592. Its totient is φ = 1552628744632.

The previous prime is 1561655656027. The next prime is 1561655656147. The reversal of 1561655656111 is 1116565561651.

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 1561655656111 - 2¹¹ = 1561655654063 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561655656151) 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, 4513455481 + ... + 4513455826.

It is an arithmetic number, because the mean of its divisors is an integer number (392670641898).

Almost surely, 2^{1561655656111} is an apocalyptic number.

1561655656111 is a deficient number, since it is larger than the sum of its proper divisors (9026911481).

1561655656111 is an equidigital number, since it uses as much as digits as its factorization.

1561655656111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9026911480.

The product of its digits is 810000, while the sum is 49.

The spelling of 1561655656111 in words is "one trillion, five hundred sixty-one billion, six hundred fifty-five million, six hundred fifty-six thousand, one hundred eleven".