21261050106161 has 4 divisors (see below), whose sum is σ = 21261969844212. Its totient is φ = 21260130368112.

The previous prime is 21261050106139. The next prime is 21261050106223. The reversal of 21261050106161 is 16160105016212.

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 32509893025 + 21228540213136 = 180305^2 + 4607444^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21261050106161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261050106761) 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, 459834350 + ... + 459880583.

It is an arithmetic number, because the mean of its divisors is an integer number (5315492461053).

Almost surely, 2^{21261050106161} is an apocalyptic number.

It is an amenable number.

21261050106161 is a deficient number, since it is larger than the sum of its proper divisors (919738051).

21261050106161 is an equidigital number, since it uses as much as digits as its factorization.

21261050106161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 919738050.

The product of its (nonzero) digits is 4320, while the sum is 32.

The spelling of 21261050106161 in words is "twenty-one trillion, two hundred sixty-one billion, fifty million, one hundred six thousand, one hundred sixty-one".