21255551433155 has 16 divisors (see below), whose sum is σ = 27583644493440. Its totient is φ = 15630731856768.

The previous prime is 21255551433073. The next prime is 21255551433169. The reversal of 21255551433155 is 55133415555212.

It is a cyclic number.

It is not a de Polignac number, because 21255551433155 - 2²⁸ = 21255282997699 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 684102632 + ... + 684133701.

It is an arithmetic number, because the mean of its divisors is an integer number (1723977780840).

Almost surely, 2^{21255551433155} is an apocalyptic number.

21255551433155 is a deficient number, since it is larger than the sum of its proper divisors (6328093060285).

21255551433155 is a wasteful number, since it uses less digits than its factorization.

21255551433155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1368236590.

The product of its digits is 2250000, while the sum is 47.

Adding to 21255551433155 its reverse (55133415555212), we get a palindrome (76388966988367).

The spelling of 21255551433155 in words is "twenty-one trillion, two hundred fifty-five billion, five hundred fifty-one million, four hundred thirty-three thousand, one hundred fifty-five".