21213166309 has 2 divisors, whose sum is σ = 21213166310. Its totient is φ = 21213166308.

The previous prime is 21213166283. The next prime is 21213166333. The reversal of 21213166309 is 90366131212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11071669284 + 10141497025 = 105222^2 + 100705^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213166309 - 2¹³ = 21213158117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213166339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606583154 + 10606583155.

It is an arithmetic number, because the mean of its divisors is an integer number (10606583155).

Almost surely, 2^21213166309 is an apocalyptic number.

It is an amenable number.

21213166309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213166309 is an equidigital number, since it uses as much as digits as its factorization.

21213166309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11664, while the sum is 34.

The spelling of 21213166309 in words is "twenty-one billion, two hundred thirteen million, one hundred sixty-six thousand, three hundred nine".