20556550209 has 16 divisors (see below), whose sum is σ = 29553096384. Its totient is φ = 12634756800.

The previous prime is 20556550199. The next prime is 20556550253. The reversal of 20556550209 is 90205565502.

It is not a de Polignac number, because 20556550209 - 2⁵ = 20556550177 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20556557209) 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, 288987 + ... + 353024.

It is an arithmetic number, because the mean of its divisors is an integer number (1847068524).

Almost surely, 2^20556550209 is an apocalyptic number.

It is an amenable number.

20556550209 is a deficient number, since it is larger than the sum of its proper divisors (8996546175).

20556550209 is a wasteful number, since it uses less digits than its factorization.

20556550209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642848.

The product of its (nonzero) digits is 135000, while the sum is 39.

The spelling of 20556550209 in words is "twenty billion, five hundred fifty-six million, five hundred fifty thousand, two hundred nine".