1361111561 has 4 divisors (see below), whose sum is σ = 1361266500. Its totient is φ = 1360956624.

The previous prime is 1361111539. The next prime is 1361111567. The reversal of 1361111561 is 1651111631.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1651111631 = 13 ⋅127008587.

It can be written as a sum of positive squares in 2 ways, for example, as 560221561 + 800890000 = 23669^2 + 28300^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1361111561 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 1361111561.

It is not an unprimeable number, because it can be changed into a prime (1361111567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63446 + ... + 82143.

It is an arithmetic number, because the mean of its divisors is an integer number (340316625).

Almost surely, 2^1361111561 is an apocalyptic number.

It is an amenable number.

1361111561 is a deficient number, since it is larger than the sum of its proper divisors (154939).

1361111561 is an equidigital number, since it uses as much as digits as its factorization.

1361111561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154938.

The product of its digits is 540, while the sum is 26.

The square root of 1361111561 is about 36893.2454658031. The cubic root of 1361111561 is about 1108.2334156268.

The spelling of 1361111561 in words is "one billion, three hundred sixty-one million, one hundred eleven thousand, five hundred sixty-one".