210001009 has 2 divisors, whose sum is σ = 210001010. Its totient is φ = 210001008.

The previous prime is 210001007. The next prime is 210001021. The reversal of 210001009 is 900100012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199600384 + 10400625 = 14128^2 + 3225^2 .

It is a cyclic number.

It is not a de Polignac number, because 210001009 - 2¹ = 210001007 is a prime.

Together with 210001007, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 210001009.

It is not a weakly prime, because it can be changed into another prime (210001003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105000504 + 105000505.

It is an arithmetic number, because the mean of its divisors is an integer number (105000505).

Almost surely, 2^210001009 is an apocalyptic number.

It is an amenable number.

210001009 is a deficient number, since it is larger than the sum of its proper divisors (1).

210001009 is an equidigital number, since it uses as much as digits as its factorization.

210001009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 210001009 is about 14491.4115599551. The cubic root of 210001009 is about 594.3931472458.

The spelling of 210001009 in words is "two hundred ten million, one thousand, nine".