3581561 has 4 divisors (see below), whose sum is σ = 3617124. Its totient is φ = 3546000.

The previous prime is 3581551. The next prime is 3581579. The reversal of 3581561 is 1651853.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1651853 = 7 ⋅235979.

It can be written as a sum of positive squares in 2 ways, for example, as 2621161 + 960400 = 1619^2 + 980^2 .

It is a cyclic number.

It is not a de Polignac number, because 3581561 - 2⁶ = 3581497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3581521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17630 + ... + 17831.

It is an arithmetic number, because the mean of its divisors is an integer number (904281).

Almost surely, 2^3581561 is an apocalyptic number.

It is an amenable number.

3581561 is a deficient number, since it is larger than the sum of its proper divisors (35563).

3581561 is a wasteful number, since it uses less digits than its factorization.

3581561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35562.

The product of its digits is 3600, while the sum is 29.

The square root of 3581561 is about 1892.5012549533. The cubic root of 3581561 is about 152.9997721671. Note that the first 3 decimals are identical.

The spelling of 3581561 in words is "three million, five hundred eighty-one thousand, five hundred sixty-one".