21611764766689 has 2 divisors, whose sum is σ = 21611764766690. Its totient is φ = 21611764766688.

The previous prime is 21611764766651. The next prime is 21611764766759. The reversal of 21611764766689 is 98666746711612.

It is a happy number.

It is an a-pointer prime, because the next prime (21611764766759) can be obtained adding 21611764766689 to its sum of digits (70).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13384000312225 + 8227764454464 = 3658415^2 + 2868408^2 .

It is a cyclic number.

It is not a de Polignac number, because 21611764766689 - 2¹⁵ = 21611764733921 is a prime.

It is not a weakly prime, because it can be changed into another prime (21611764766609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805882383344 + 10805882383345.

It is an arithmetic number, because the mean of its divisors is an integer number (10805882383345).

Almost surely, 2^{21611764766689} is an apocalyptic number.

It is an amenable number.

21611764766689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21611764766689 is an equidigital number, since it uses as much as digits as its factorization.

21611764766689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 219469824, while the sum is 70.

The spelling of 21611764766689 in words is "twenty-one trillion, six hundred eleven billion, seven hundred sixty-four million, seven hundred sixty-six thousand, six hundred eighty-nine".