21720220552205 has 8 divisors (see below), whose sum is σ = 29787731043072. Its totient is φ = 14893865521488.

The previous prime is 21720220552183. The next prime is 21720220552207. The reversal of 21720220552205 is 50225502202712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21720220552205 - 2¹² = 21720220548109 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 620577730063 = 21720220552205 / (2 + 1 + 7 + 2 + 0 + 2 + 2 + 0 + 5 + 5 + 2 + 2 + 0 + 5).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720220552207) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 310288864997 + ... + 310288865066.

It is an arithmetic number, because the mean of its divisors is an integer number (3723466380384).

Almost surely, 2^{21720220552205} is an apocalyptic number.

It is an amenable number.

21720220552205 is a deficient number, since it is larger than the sum of its proper divisors (8067510490867).

21720220552205 is an equidigital number, since it uses as much as digits as its factorization.

21720220552205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620577730075.

The product of its (nonzero) digits is 56000, while the sum is 35.

Adding to 21720220552205 its reverse (50225502202712), we get a palindrome (71945722754917).

The spelling of 21720220552205 in words is "twenty-one trillion, seven hundred twenty billion, two hundred twenty million, five hundred fifty-two thousand, two hundred five".