21213044009 has 2 divisors, whose sum is σ = 21213044010. Its totient is φ = 21213044008.

The previous prime is 21213043987. The next prime is 21213044029. The reversal of 21213044009 is 90044031212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20526865984 + 686178025 = 143272^2 + 26195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213044009 is a prime.

It is a super-2 number, since 2×21213044009² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21213044029) 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, 10606522004 + 10606522005.

It is an arithmetic number, because the mean of its divisors is an integer number (10606522005).

Almost surely, 2^21213044009 is an apocalyptic number.

It is an amenable number.

21213044009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213044009 is an equidigital number, since it uses as much as digits as its factorization.

21213044009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

The spelling of 21213044009 in words is "twenty-one billion, two hundred thirteen million, forty-four thousand, nine".