21009874736309 has 2 divisors, whose sum is σ = 21009874736310. Its totient is φ = 21009874736308.

The previous prime is 21009874736303. The next prime is 21009874736497. The reversal of 21009874736309 is 90363747890012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19954508900209 + 1055365836100 = 4467047^2 + 1027310^2 .

It is a cyclic number.

It is not a de Polignac number, because 21009874736309 - 2⁴ = 21009874736293 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21009874736303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10504937368154 + 10504937368155.

It is an arithmetic number, because the mean of its divisors is an integer number (10504937368155).

Almost surely, 2^{21009874736309} is an apocalyptic number.

It is an amenable number.

21009874736309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21009874736309 is an equidigital number, since it uses as much as digits as its factorization.

21009874736309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13716864, while the sum is 59.

The spelling of 21009874736309 in words is "twenty-one trillion, nine billion, eight hundred seventy-four million, seven hundred thirty-six thousand, three hundred nine".