21223061321555 has 4 divisors (see below), whose sum is σ = 25467673585872. Its totient is φ = 16978449057240.

The previous prime is 21223061321503. The next prime is 21223061321557. The reversal of 21223061321555 is 55512316032212.

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

It is not a de Polignac number, because 21223061321555 - 2⁴² = 16825014810451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21223061321557) 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, 2122306132151 + ... + 2122306132160.

It is an arithmetic number, because the mean of its divisors is an integer number (6366918396468).

Almost surely, 2^{21223061321555} is an apocalyptic number.

21223061321555 is a deficient number, since it is larger than the sum of its proper divisors (4244612264317).

21223061321555 is an equidigital number, since it uses as much as digits as its factorization.

21223061321555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4244612264316.

The product of its (nonzero) digits is 108000, while the sum is 38.

Adding to 21223061321555 its reverse (55512316032212), we get a palindrome (76735377353767).

The spelling of 21223061321555 in words is "twenty-one trillion, two hundred twenty-three billion, sixty-one million, three hundred twenty-one thousand, five hundred fifty-five".