1191581 has 8 divisors (see below), whose sum is σ = 1305720. Its totient is φ = 1082368.

The previous prime is 1191577. The next prime is 1191601. The reversal of 1191581 is 1851911.

It can be written as a sum of positive squares in 4 ways, for example, as 688900 + 502681 = 830^2 + 709^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1191581 - 2² = 1191577 is a prime.

It is a super-2 number, since 2×1191581² = 2839730559122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1191581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191551) 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 7 ways as a sum of consecutive naturals, for example, 716 + ... + 1701.

It is an arithmetic number, because the mean of its divisors is an integer number (163215).

2^1191581 is an apocalyptic number.

It is an amenable number.

1191581 is a deficient number, since it is larger than the sum of its proper divisors (114139).

1191581 is a wasteful number, since it uses less digits than its factorization.

1191581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2463.

The product of its digits is 360, while the sum is 26.

The square root of 1191581 is about 1091.5956210978. The cubic root of 1191581 is about 106.0167589498.

The spelling of 1191581 in words is "one million, one hundred ninety-one thousand, five hundred eighty-one".