21634221056155 has 16 divisors (see below), whose sum is σ = 26306421465600. Its totient is φ = 17077418298720.

The previous prime is 21634221056153. The next prime is 21634221056167. The reversal of 21634221056155 is 55165012243612.

It is not a de Polignac number, because 21634221056155 - 2¹ = 21634221056153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21634221056153) 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, 16811085 + ... + 18052174.

It is an arithmetic number, because the mean of its divisors is an integer number (1644151341600).

Almost surely, 2^{21634221056155} is an apocalyptic number.

21634221056155 is a deficient number, since it is larger than the sum of its proper divisors (4672200409445).

21634221056155 is a wasteful number, since it uses less digits than its factorization.

21634221056155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34864914.

The product of its (nonzero) digits is 432000, while the sum is 43.

Adding to 21634221056155 its reverse (55165012243612), we get a palindrome (76799233299767).

The spelling of 21634221056155 in words is "twenty-one trillion, six hundred thirty-four billion, two hundred twenty-one million, fifty-six thousand, one hundred fifty-five".