21013013209 has 2 divisors, whose sum is σ = 21013013210. Its totient is φ = 21013013208.

The previous prime is 21013013167. The next prime is 21013013213. The reversal of 21013013209 is 90231031012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18988013209 + 2025000000 = 137797^2 + 45000^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013013209 - 2¹³ = 21013005017 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21013013209.

It is not a weakly prime, because it can be changed into another prime (21013013269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506506604 + 10506506605.

It is an arithmetic number, because the mean of its divisors is an integer number (10506506605).

Almost surely, 2^21013013209 is an apocalyptic number.

It is an amenable number.

21013013209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013013209 is an equidigital number, since it uses as much as digits as its factorization.

21013013209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 324, while the sum is 22.

The spelling of 21013013209 in words is "twenty-one billion, thirteen million, thirteen thousand, two hundred nine".