21010112909 has 2 divisors, whose sum is σ = 21010112910. Its totient is φ = 21010112908.

The previous prime is 21010112899. The next prime is 21010112947. The reversal of 21010112909 is 90921101012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20981522500 + 28590409 = 144850^2 + 5347^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010112909 - 2²⁰ = 21009064333 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21010112969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505056454 + 10505056455.

It is an arithmetic number, because the mean of its divisors is an integer number (10505056455).

Almost surely, 2^21010112909 is an apocalyptic number.

It is an amenable number.

21010112909 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010112909 is an equidigital number, since it uses as much as digits as its factorization.

21010112909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 26.

The spelling of 21010112909 in words is "twenty-one billion, ten million, one hundred twelve thousand, nine hundred nine".