21344221655 has 4 divisors (see below), whose sum is σ = 25613065992. Its totient is φ = 17075377320.

The previous prime is 21344221643. The next prime is 21344221673. The reversal of 21344221655 is 55612244312.

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

It is not a de Polignac number, because 21344221655 - 2¹⁴ = 21344205271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2134422161 + ... + 2134422170.

It is an arithmetic number, because the mean of its divisors is an integer number (6403266498).

Almost surely, 2^21344221655 is an apocalyptic number.

21344221655 is a deficient number, since it is larger than the sum of its proper divisors (4268844337).

21344221655 is an equidigital number, since it uses as much as digits as its factorization.

21344221655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4268844336.

The product of its digits is 57600, while the sum is 35.

Adding to 21344221655 its reverse (55612244312), we get a palindrome (76956465967).

The spelling of 21344221655 in words is "twenty-one billion, three hundred forty-four million, two hundred twenty-one thousand, six hundred fifty-five".