21389686189 has 2 divisors, whose sum is σ = 21389686190. Its totient is φ = 21389686188.

The previous prime is 21389686133. The next prime is 21389686237. The reversal of 21389686189 is 98168698312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19226040964 + 2163645225 = 138658^2 + 46515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21389686189 - 2⁷ = 21389686061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21389686789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10694843094 + 10694843095.

It is an arithmetic number, because the mean of its divisors is an integer number (10694843095).

Almost surely, 2^21389686189 is an apocalyptic number.

It is an amenable number.

21389686189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21389686189 is an equidigital number, since it uses as much as digits as its factorization.

21389686189 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8957952, while the sum is 61.

The spelling of 21389686189 in words is "twenty-one billion, three hundred eighty-nine million, six hundred eighty-six thousand, one hundred eighty-nine".