1121581 has 4 divisors (see below), whose sum is σ = 1151932. Its totient is φ = 1091232.

The previous prime is 1121557. The next prime is 1121599. The reversal of 1121581 is 1851211.

1121581 = T₈₃ + T₈₄ + ... + T₁₉₃.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1851211 = 397 ⋅4663.

It can be written as a sum of positive squares in 2 ways, for example, as 1010025 + 111556 = 1005^2 + 334^2 .

It is a cyclic number.

It is not a de Polignac number, because 1121581 - 2⁷ = 1121453 is a prime.

It is a super-2 number, since 2×1121581² = 2515887879122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1124581) 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, 15120 + ... + 15193.

It is an arithmetic number, because the mean of its divisors is an integer number (287983).

2^1121581 is an apocalyptic number.

It is an amenable number.

1121581 is a deficient number, since it is larger than the sum of its proper divisors (30351).

1121581 is an equidigital number, since it uses as much as digits as its factorization.

1121581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30350.

The product of its digits is 80, while the sum is 19.

The square root of 1121581 is about 1059.0472133007. The cubic root of 1121581 is about 103.8987241407.

Adding to 1121581 its reverse (1851211), we get a palindrome (2972792).

The spelling of 1121581 in words is "one million, one hundred twenty-one thousand, five hundred eighty-one".