20290561 has 4 divisors (see below), whose sum is σ = 20312512. Its totient is φ = 20268612.

The previous prime is 20290559. The next prime is 20290579. The reversal of 20290561 is 16509202.

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 not a de Polignac number, because 20290561 - 2¹ = 20290559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20290591) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9525 + ... + 11458.

It is an arithmetic number, because the mean of its divisors is an integer number (5078128).

Almost surely, 2^20290561 is an apocalyptic number.

It is an amenable number.

20290561 is a deficient number, since it is larger than the sum of its proper divisors (21951).

20290561 is an equidigital number, since it uses as much as digits as its factorization.

20290561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21950.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 20290561 is about 4504.5045232523. The cubic root of 20290561 is about 272.7499533023.

Adding to 20290561 its reverse (16509202), we get a palindrome (36799763).

The spelling of 20290561 in words is "twenty million, two hundred ninety thousand, five hundred sixty-one".