20544581 has 4 divisors (see below), whose sum is σ = 20562732. Its totient is φ = 20526432.

The previous prime is 20544571. The next prime is 20544611. The reversal of 20544581 is 18544502.

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 3363556 + 17181025 = 1834^2 + 4145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20544581 is a prime.

It is a super-2 number, since 2×20544581² = 844159616931122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20544521) 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, 7256 + ... + 9681.

It is an arithmetic number, because the mean of its divisors is an integer number (5140683).

Almost surely, 2^20544581 is an apocalyptic number.

It is an amenable number.

20544581 is a deficient number, since it is larger than the sum of its proper divisors (18151).

20544581 is a wasteful number, since it uses less digits than its factorization.

20544581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18150.

The product of its (nonzero) digits is 6400, while the sum is 29.

The square root of 20544581 is about 4532.6130432676. The cubic root of 20544581 is about 273.8834329317.

The spelling of 20544581 in words is "twenty million, five hundred forty-four thousand, five hundred eighty-one".