21644761067 has 2 divisors, whose sum is σ = 21644761068. Its totient is φ = 21644761066.

The previous prime is 21644761049. The next prime is 21644761111. The reversal of 21644761067 is 76016744612.

It is an a-pointer prime, because the next prime (21644761111) can be obtained adding 21644761067 to its sum of digits (44).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21644761067 - 2¹⁴ = 21644744683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21644761027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822380533 + 10822380534.

It is an arithmetic number, because the mean of its divisors is an integer number (10822380534).

Almost surely, 2^21644761067 is an apocalyptic number.

21644761067 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644761067 is an equidigital number, since it uses as much as digits as its factorization.

21644761067 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 338688, while the sum is 44.

The spelling of 21644761067 in words is "twenty-one billion, six hundred forty-four million, seven hundred sixty-one thousand, sixty-seven".