20202561 has 16 divisors (see below), whose sum is σ = 30627520. Its totient is φ = 13154400.

The previous prime is 20202557. The next prime is 20202571. The reversal of 20202561 is 16520202.

It is not a de Polignac number, because 20202561 - 2² = 20202557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20202571) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7540 + ... + 9861.

It is an arithmetic number, because the mean of its divisors is an integer number (1914220).

Almost surely, 2^20202561 is an apocalyptic number.

It is an amenable number.

20202561 is a deficient number, since it is larger than the sum of its proper divisors (10424959).

20202561 is a wasteful number, since it uses less digits than its factorization.

20202561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17453 (or 17447 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 20202561 is about 4494.7259093297. The cubic root of 20202561 is about 272.3550771075.

Adding to 20202561 its reverse (16520202), we get a palindrome (36722763).

The spelling of 20202561 in words is "twenty million, two hundred two thousand, five hundred sixty-one".