20561245 has 16 divisors (see below), whose sum is σ = 26500608. Its totient is φ = 15258880.

The previous prime is 20561239. The next prime is 20561257. The reversal of 20561245 is 54216502.

It is not a de Polignac number, because 20561245 - 2³ = 20561237 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4332 + ... + 7738.

It is an arithmetic number, because the mean of its divisors is an integer number (1656288).

Almost surely, 2^20561245 is an apocalyptic number.

It is an amenable number.

20561245 is a deficient number, since it is larger than the sum of its proper divisors (5939363).

20561245 is a wasteful number, since it uses less digits than its factorization.

20561245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3500.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 20561245 is about 4534.4509039133. The cubic root of 20561245 is about 273.9574631607.

Adding to 20561245 its reverse (54216502), we get a palindrome (74777747).

The spelling of 20561245 in words is "twenty million, five hundred sixty-one thousand, two hundred forty-five".