21001107989 has 2 divisors, whose sum is σ = 21001107990. Its totient is φ = 21001107988.

The previous prime is 21001107971. The next prime is 21001108021. The reversal of 21001107989 is 98970110012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17307507364 + 3693600625 = 131558^2 + 60775^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001107989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001107929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500553994 + 10500553995.

It is an arithmetic number, because the mean of its divisors is an integer number (10500553995).

Almost surely, 2^21001107989 is an apocalyptic number.

It is an amenable number.

21001107989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001107989 is an equidigital number, since it uses as much as digits as its factorization.

21001107989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 38.

The spelling of 21001107989 in words is "twenty-one billion, one million, one hundred seven thousand, nine hundred eighty-nine".