21221201317 has 2 divisors, whose sum is σ = 21221201318. Its totient is φ = 21221201316.

The previous prime is 21221201237. The next prime is 21221201329. The reversal of 21221201317 is 71310212212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19653516481 + 1567684836 = 140191^2 + 39594^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221201317 - 2⁷ = 21221201189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221201387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610600658 + 10610600659.

It is an arithmetic number, because the mean of its divisors is an integer number (10610600659).

Almost surely, 2^21221201317 is an apocalyptic number.

It is an amenable number.

21221201317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221201317 is an equidigital number, since it uses as much as digits as its factorization.

21221201317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 336, while the sum is 22.

Adding to 21221201317 its reverse (71310212212), we get a palindrome (92531413529).

The spelling of 21221201317 in words is "twenty-one billion, two hundred twenty-one million, two hundred one thousand, three hundred seventeen".