20561056 has 12 divisors (see below), whose sum is σ = 40479642. Its totient is φ = 10280512.

The previous prime is 20561053. The next prime is 20561069. The reversal of 20561056 is 65016502.

It can be written as a sum of positive squares in only one way, i.e., 15085456 + 5475600 = 3884^2 + 2340^2 .

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 20561056.

It is not an unprimeable number, because it can be changed into a prime (20561053) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321235 + ... + 321298.

Almost surely, 2^20561056 is an apocalyptic number.

It is an amenable number.

20561056 is a deficient number, since it is larger than the sum of its proper divisors (19918586).

20561056 is an equidigital number, since it uses as much as digits as its factorization.

20561056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642543 (or 642535 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 20561056 is about 4534.4300634148. The cubic root of 20561056 is about 273.9566237479.

Adding to 20561056 its reverse (65016502), we get a palindrome (85577558).

The spelling of 20561056 in words is "twenty million, five hundred sixty-one thousand, fifty-six".