20020561 has 4 divisors (see below), whose sum is σ = 21840624. Its totient is φ = 18200500.

The previous prime is 20020541. The next prime is 20020571. The reversal of 20020561 is 16502002.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20020561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20020501) 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, 910015 + ... + 910036.

It is an arithmetic number, because the mean of its divisors is an integer number (5460156).

Almost surely, 2^20020561 is an apocalyptic number.

It is an amenable number.

20020561 is a deficient number, since it is larger than the sum of its proper divisors (1820063).

20020561 is a wasteful number, since it uses less digits than its factorization.

20020561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1820062.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 20020561 is about 4474.4341541697. The cubic root of 20020561 is about 271.5347483695.

Adding to 20020561 its reverse (16502002), we get a palindrome (36522563).

The spelling of 20020561 in words is "twenty million, twenty thousand, five hundred sixty-one".