20005111506561 has 16 divisors (see below), whose sum is σ = 28731043737600. Its totient is φ = 12345370353360.

The previous prime is 20005111506553. The next prime is 20005111506587. The reversal of 20005111506561 is 16560511150002.

It is not a de Polignac number, because 20005111506561 - 2³ = 20005111506553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20005111516561) 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, 4676274511 + ... + 4676278788.

It is an arithmetic number, because the mean of its divisors is an integer number (1795690233600).

Almost surely, 2^{20005111506561} is an apocalyptic number.

It is an amenable number.

20005111506561 is a deficient number, since it is larger than the sum of its proper divisors (8725932231039).

20005111506561 is a wasteful number, since it uses less digits than its factorization.

20005111506561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9352553356.

The product of its (nonzero) digits is 9000, while the sum is 33.

Adding to 20005111506561 its reverse (16560511150002), we get a palindrome (36565622656563).

The spelling of 20005111506561 in words is "twenty trillion, five billion, one hundred eleven million, five hundred six thousand, five hundred sixty-one".