21020020001689 has 2 divisors, whose sum is σ = 21020020001690. Its totient is φ = 21020020001688.

The previous prime is 21020020001671. The next prime is 21020020001711. The reversal of 21020020001689 is 98610002002012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19607998760464 + 1412021241225 = 4428092^2 + 1188285^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020020001689 - 2¹⁷ = 21020019870617 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21020020001689.

It is not a weakly prime, because it can be changed into another prime (21020020001639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510010000844 + 10510010000845.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010000845).

Almost surely, 2^{21020020001689} is an apocalyptic number.

It is an amenable number.

21020020001689 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020020001689 is an equidigital number, since it uses as much as digits as its factorization.

21020020001689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 31.

The spelling of 21020020001689 in words is "twenty-one trillion, twenty billion, twenty million, one thousand, six hundred eighty-nine".