21640767737 has 2 divisors, whose sum is σ = 21640767738. Its totient is φ = 21640767736.

The previous prime is 21640767719. The next prime is 21640767787. The reversal of 21640767737 is 73776704612.

It is an a-pointer prime, because the next prime (21640767787) can be obtained adding 21640767737 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21389355001 + 251412736 = 146251^2 + 15856^2 .

It is a cyclic number.

It is not a de Polignac number, because 21640767737 - 2¹⁰ = 21640766713 is a prime.

It is not a weakly prime, because it can be changed into another prime (21640767787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10820383868 + 10820383869.

It is an arithmetic number, because the mean of its divisors is an integer number (10820383869).

Almost surely, 2^21640767737 is an apocalyptic number.

It is an amenable number.

21640767737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21640767737 is an equidigital number, since it uses as much as digits as its factorization.

21640767737 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2074464, while the sum is 50.

The spelling of 21640767737 in words is "twenty-one billion, six hundred forty million, seven hundred sixty-seven thousand, seven hundred thirty-seven".