21766337729 has 2 divisors, whose sum is σ = 21766337730. Its totient is φ = 21766337728.

The previous prime is 21766337711. The next prime is 21766337779. The reversal of 21766337729 is 92773366712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21681973504 + 84364225 = 147248^2 + 9185^2 .

It is a cyclic number.

It is not a de Polignac number, because 21766337729 - 2²⁰ = 21765289153 is a prime.

It is not a weakly prime, because it can be changed into another prime (21766337779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883168864 + 10883168865.

It is an arithmetic number, because the mean of its divisors is an integer number (10883168865).

Almost surely, 2^21766337729 is an apocalyptic number.

It is an amenable number.

21766337729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21766337729 is an equidigital number, since it uses as much as digits as its factorization.

21766337729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4000752, while the sum is 53.

The spelling of 21766337729 in words is "twenty-one billion, seven hundred sixty-six million, three hundred thirty-seven thousand, seven hundred twenty-nine".