20561556411 has 24 divisors (see below), whose sum is σ = 32458284144. Its totient is φ = 12439143360.

The previous prime is 20561556397. The next prime is 20561556419. The reversal of 20561556411 is 11465516502.

20561556411 is a `hidden beast` number, since 2 + 0 + 5 + 6 + 1 + 5 + 5 + 641 + 1 = 666.

It is not a de Polignac number, because 20561556411 - 2¹⁹ = 20561032123 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20561556419) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 131296 + ... + 241581.

It is an arithmetic number, because the mean of its divisors is an integer number (1352428506).

Almost surely, 2^20561556411 is an apocalyptic number.

20561556411 is a deficient number, since it is larger than the sum of its proper divisors (11896727733).

20561556411 is a wasteful number, since it uses less digits than its factorization.

20561556411 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 373451 (or 373448 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 36.

The spelling of 20561556411 in words is "twenty billion, five hundred sixty-one million, five hundred fifty-six thousand, four hundred eleven".