20561255161 has 8 divisors (see below), whose sum is σ = 20726364960. Its totient is φ = 20396391168.

The previous prime is 20561255131. The next prime is 20561255167. The reversal of 20561255161 is 16155216502.

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

It is a cyclic number.

It is not a de Polignac number, because 20561255161 - 2¹³ = 20561246969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561255167) 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, 108390 + ... + 229936.

It is an arithmetic number, because the mean of its divisors is an integer number (2590795620).

Almost surely, 2^20561255161 is an apocalyptic number.

It is an amenable number.

20561255161 is a deficient number, since it is larger than the sum of its proper divisors (165109799).

20561255161 is a wasteful number, since it uses less digits than its factorization.

20561255161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122903.

The product of its (nonzero) digits is 18000, while the sum is 34.

The spelling of 20561255161 in words is "twenty billion, five hundred sixty-one million, two hundred fifty-five thousand, one hundred sixty-one".