21988373216717 has 2 divisors, whose sum is σ = 21988373216718. Its totient is φ = 21988373216716.

The previous prime is 21988373216629. The next prime is 21988373216729. The reversal of 21988373216717 is 71761237388912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16780730552041 + 5207642664676 = 4096429^2 + 2282026^2 .

It is a cyclic number.

It is not a de Polignac number, because 21988373216717 - 2¹² = 21988373212621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21988373216317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10994186608358 + 10994186608359.

It is an arithmetic number, because the mean of its divisors is an integer number (10994186608359).

Almost surely, 2^{21988373216717} is an apocalyptic number.

It is an amenable number.

21988373216717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21988373216717 is an equidigital number, since it uses as much as digits as its factorization.

21988373216717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42674688, while the sum is 65.

The spelling of 21988373216717 in words is "twenty-one trillion, nine hundred eighty-eight billion, three hundred seventy-three million, two hundred sixteen thousand, seven hundred seventeen".