11581961 has 4 divisors (see below), whose sum is σ = 11740692. Its totient is φ = 11423232.

The previous prime is 11581957. The next prime is 11581979. The reversal of 11581961 is 16918511.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8410000 + 3171961 = 2900^2 + 1781^2 .

It is a cyclic number.

It is not a de Polignac number, because 11581961 - 2² = 11581957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (11581901) 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, 79256 + ... + 79401.

It is an arithmetic number, because the mean of its divisors is an integer number (2935173).

Almost surely, 2^11581961 is an apocalyptic number.

It is an amenable number.

11581961 is a deficient number, since it is larger than the sum of its proper divisors (158731).

11581961 is an equidigital number, since it uses as much as digits as its factorization.

11581961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158730.

The product of its digits is 2160, while the sum is 32.

The square root of 11581961 is about 3403.2280264478. The cubic root of 11581961 is about 226.2528365689.

The spelling of 11581961 in words is "eleven million, five hundred eighty-one thousand, nine hundred sixty-one".