21255663355 has 4 divisors (see below), whose sum is σ = 25506796032. Its totient is φ = 17004530680.

The previous prime is 21255663353. The next prime is 21255663367. The reversal of 21255663355 is 55336655212.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21255663355 - 2¹ = 21255663353 is a prime.

It is a super-2 number, since 2×21255663355² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21255663353) 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, 2125566331 + ... + 2125566340.

It is an arithmetic number, because the mean of its divisors is an integer number (6376699008).

Almost surely, 2^21255663355 is an apocalyptic number.

21255663355 is a deficient number, since it is larger than the sum of its proper divisors (4251132677).

21255663355 is an equidigital number, since it uses as much as digits as its factorization.

21255663355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4251132676.

The product of its digits is 810000, while the sum is 43.

The spelling of 21255663355 in words is "twenty-one billion, two hundred fifty-five million, six hundred sixty-three thousand, three hundred fifty-five".