21506201351009 has 2 divisors, whose sum is σ = 21506201351010. Its totient is φ = 21506201351008.

The previous prime is 21506201350967. The next prime is 21506201351017. The reversal of 21506201351009 is 90015310260512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21211735584400 + 294465766609 = 4605620^2 + 542647^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506201351009 - 2¹² = 21506201346913 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21506201351009.

It is not a weakly prime, because it can be changed into another prime (21506201351029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753100675504 + 10753100675505.

It is an arithmetic number, because the mean of its divisors is an integer number (10753100675505).

Almost surely, 2^{21506201351009} is an apocalyptic number.

It is an amenable number.

21506201351009 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506201351009 is an equidigital number, since it uses as much as digits as its factorization.

21506201351009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16200, while the sum is 35.

The spelling of 21506201351009 in words is "twenty-one trillion, five hundred six billion, two hundred one million, three hundred fifty-one thousand, nine".