21217311604673 has 4 divisors (see below), whose sum is σ = 21217347863088. Its totient is φ = 21217275346260.

The previous prime is 21217311604639. The next prime is 21217311604679. The reversal of 21217311604673 is 37640611371212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21217311604673 - 2⁶ = 21217311604609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21217311604679) 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, 17236811 + ... + 18426672.

It is an arithmetic number, because the mean of its divisors is an integer number (5304336965772).

Almost surely, 2^{21217311604673} is an apocalyptic number.

It is an amenable number.

21217311604673 is a deficient number, since it is larger than the sum of its proper divisors (36258415).

21217311604673 is an equidigital number, since it uses as much as digits as its factorization.

21217311604673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36258414.

The product of its (nonzero) digits is 254016, while the sum is 44.

Adding to 21217311604673 its reverse (37640611371212), we get a palindrome (58857922975885).

The spelling of 21217311604673 in words is "twenty-one trillion, two hundred seventeen billion, three hundred eleven million, six hundred four thousand, six hundred seventy-three".