2163635221261 has 4 divisors (see below), whose sum is σ = 2163795777532. Its totient is φ = 2163474664992.

The previous prime is 2163635221247. The next prime is 2163635221289. The reversal of 2163635221261 is 1621225363612.

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 1372013968900 + 791621252361 = 1171330^2 + 889731^2 .

It is a cyclic number.

It is not a de Polignac number, because 2163635221261 - 2⁵ = 2163635221229 is a prime.

It is a super-2 number, since 2×2163635221261² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2163635291261) 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, 80257920 + ... + 80284873.

It is an arithmetic number, because the mean of its divisors is an integer number (540948944383).

Almost surely, 2^{2163635221261} is an apocalyptic number.

It is an amenable number.

2163635221261 is a deficient number, since it is larger than the sum of its proper divisors (160556271).

2163635221261 is a wasteful number, since it uses less digits than its factorization.

2163635221261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160556270.

The product of its digits is 155520, while the sum is 40.

The spelling of 2163635221261 in words is "two trillion, one hundred sixty-three billion, six hundred thirty-five million, two hundred twenty-one thousand, two hundred sixty-one".