1161561 has 4 divisors (see below), whose sum is σ = 1548752. Its totient is φ = 774372.

The previous prime is 1161553. The next prime is 1161581. The reversal of 1161561 is 1651611.

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 not a de Polignac number, because 1161561 - 2³ = 1161553 is a prime.

It is a D-number.

It is a Duffinian number.

1161561 is a lucky number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (1161521) 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, 193591 + ... + 193596.

It is an arithmetic number, because the mean of its divisors is an integer number (387188).

2^1161561 is an apocalyptic number.

It is an amenable number.

1161561 is a deficient number, since it is larger than the sum of its proper divisors (387191).

1161561 is an equidigital number, since it uses as much as digits as its factorization.

1161561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 387190.

The product of its digits is 180, while the sum is 21.

The square root of 1161561 is about 1077.7573938508. The cubic root of 1161561 is about 105.1188676500.

The spelling of 1161561 in words is "one million, one hundred sixty-one thousand, five hundred sixty-one".