21221016926717 has 2 divisors, whose sum is σ = 21221016926718. Its totient is φ = 21221016926716.

The previous prime is 21221016926651. The next prime is 21221016926749. The reversal of 21221016926717 is 71762961012212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14625951223321 + 6595065703396 = 3824389^2 + 2568086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221016926717 - 2²⁴ = 21221000149501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221016926617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610508463358 + 10610508463359.

It is an arithmetic number, because the mean of its divisors is an integer number (10610508463359).

Almost surely, 2^{21221016926717} is an apocalyptic number.

It is an amenable number.

21221016926717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221016926717 is an equidigital number, since it uses as much as digits as its factorization.

21221016926717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 254016, while the sum is 47.

Adding to 21221016926717 its reverse (71762961012212), we get a palindrome (92983977938929).

The spelling of 21221016926717 in words is "twenty-one trillion, two hundred twenty-one billion, sixteen million, nine hundred twenty-six thousand, seven hundred seventeen".