21241660777 has 2 divisors, whose sum is σ = 21241660778. Its totient is φ = 21241660776.

The previous prime is 21241660751. The next prime is 21241660807. The reversal of 21241660777 is 77706614212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20140151056 + 1101509721 = 141916^2 + 33189^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21241660777 is a prime.

It is not a weakly prime, because it can be changed into another prime (21241660747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620830388 + 10620830389.

It is an arithmetic number, because the mean of its divisors is an integer number (10620830389).

Almost surely, 2^21241660777 is an apocalyptic number.

It is an amenable number.

21241660777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21241660777 is an equidigital number, since it uses as much as digits as its factorization.

21241660777 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 197568, while the sum is 43.

The spelling of 21241660777 in words is "twenty-one billion, two hundred forty-one million, six hundred sixty thousand, seven hundred seventy-seven".