20559561 has 8 divisors (see below), whose sum is σ = 29904864. Its totient is φ = 12460320.

The previous prime is 20559557. The next prime is 20559563. The reversal of 20559561 is 16595502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20559561 - 2² = 20559557 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 623017 = 20559561 / (2 + 0 + 5 + 5 + 9 + 5 + 6 + 1).

It is not an unprimeable number, because it can be changed into a prime (20559563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 311476 + ... + 311541.

It is an arithmetic number, because the mean of its divisors is an integer number (3738108).

Almost surely, 2^20559561 is an apocalyptic number.

It is an amenable number.

20559561 is a deficient number, since it is larger than the sum of its proper divisors (9345303).

20559561 is a wasteful number, since it uses less digits than its factorization.

20559561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 623031.

The product of its (nonzero) digits is 13500, while the sum is 33.

The square root of 20559561 is about 4534.2652105937. The cubic root of 20559561 is about 273.9499837666.

The spelling of 20559561 in words is "twenty million, five hundred fifty-nine thousand, five hundred sixty-one".