21010000009 has 2 divisors, whose sum is σ = 21010000010. Its totient is φ = 21010000008.

The previous prime is 21009999971. The next prime is 21010000013. The reversal of 21010000009 is 90000001012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19776234384 + 1233765625 = 140628^2 + 35125^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21010000009 is a prime.

It is not a weakly prime, because it can be changed into another prime (21010004009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505000004 + 10505000005.

It is an arithmetic number, because the mean of its divisors is an integer number (10505000005).

Almost surely, 2^21010000009 is an apocalyptic number.

It is an amenable number.

21010000009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010000009 is an equidigital number, since it uses as much as digits as its factorization.

21010000009 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 spelling of 21010000009 in words is "twenty-one billion, ten million, nine", and thus it is an aban number and an uban number.