20581345 has 8 divisors (see below), whose sum is σ = 24753960. Its totient is φ = 16427520.

The previous prime is 20581333. The next prime is 20581367. The reversal of 20581345 is 54318502.

It can be written as a sum of positive squares in 4 ways, for example, as 87616 + 20493729 = 296^2 + 4527^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-20581345 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2160 + ... + 6769.

It is an arithmetic number, because the mean of its divisors is an integer number (3094245).

Almost surely, 2^20581345 is an apocalyptic number.

It is an amenable number.

20581345 is a deficient number, since it is larger than the sum of its proper divisors (4172615).

20581345 is an equidigital number, since it uses as much as digits as its factorization.

20581345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9395.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 20581345 is about 4536.6667278962. Note that the first 3 decimals coincide. The cubic root of 20581345 is about 274.0467047030.

Adding to 20581345 its reverse (54318502), we get a palindrome (74899847).

It can be divided in two parts, 2058 and 1345, that added together give a triangular number (3403 = T₈₂).

The spelling of 20581345 in words is "twenty million, five hundred eighty-one thousand, three hundred forty-five".