21506201351017 has 2 divisors, whose sum is σ = 21506201351018. Its totient is φ = 21506201351016.

The previous prime is 21506201351009. The next prime is 21506201351021. The reversal of 21506201351017 is 71015310260512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14083687974976 + 7422513376041 = 3752824^2 + 2724429^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506201351017 - 2³ = 21506201351009 is a prime.

It is not a weakly prime, because it can be changed into another prime (21506201351057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753100675508 + 10753100675509.

It is an arithmetic number, because the mean of its divisors is an integer number (10753100675509).

Almost surely, 2^{21506201351017} is an apocalyptic number.

It is an amenable number.

21506201351017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506201351017 is an equidigital number, since it uses as much as digits as its factorization.

21506201351017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12600, while the sum is 34.

The spelling of 21506201351017 in words is "twenty-one trillion, five hundred six billion, two hundred one million, three hundred fifty-one thousand, seventeen".