20215650500561 has 4 divisors (see below), whose sum is σ = 20239349974452. Its totient is φ = 20191951026672.

The previous prime is 20215650500537. The next prime is 20215650500597. The reversal of 20215650500561 is 16500505651202.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 333361890625 + 19882288609936 = 577375^2 + 4458956^2 .

It is a cyclic number.

It is not a de Polignac number, because 20215650500561 - 2⁶ = 20215650500497 is a prime.

It is a super-2 number, since 2×20215650500561² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20215650500161) 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, 11849735666 + ... + 11849737371.

It is an arithmetic number, because the mean of its divisors is an integer number (5059837493613).

Almost surely, 2^{20215650500561} is an apocalyptic number.

It is an amenable number.

20215650500561 is a deficient number, since it is larger than the sum of its proper divisors (23699473891).

20215650500561 is an equidigital number, since it uses as much as digits as its factorization.

20215650500561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23699473890.

The product of its (nonzero) digits is 90000, while the sum is 38.

The spelling of 20215650500561 in words is "twenty trillion, two hundred fifteen billion, six hundred fifty million, five hundred thousand, five hundred sixty-one".