1161061205581 has 4 divisors (see below), whose sum is σ = 1161735067552. Its totient is φ = 1160387343612.

The previous prime is 1161061205477. The next prime is 1161061205621. The reversal of 1161061205581 is 1855021601611.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1161061205581 is a prime.

It is a super-2 number, since 2×1161061205581² (a number of 25 digits) contains 22 as substring.

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 1161061205581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1161061208581) 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, 336928401 + ... + 336931846.

It is an arithmetic number, because the mean of its divisors is an integer number (290433766888).

Almost surely, 2^{1161061205581} is an apocalyptic number.

It is an amenable number.

1161061205581 is a deficient number, since it is larger than the sum of its proper divisors (673861971).

1161061205581 is an equidigital number, since it uses as much as digits as its factorization.

1161061205581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673861970.

The product of its (nonzero) digits is 14400, while the sum is 37.

The spelling of 1161061205581 in words is "one trillion, one hundred sixty-one billion, sixty-one million, two hundred five thousand, five hundred eighty-one".