21253431435217 has 2 divisors, whose sum is σ = 21253431435218. Its totient is φ = 21253431435216.

The previous prime is 21253431435179. The next prime is 21253431435259. The reversal of 21253431435217 is 71253413435212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19364893109136 + 1888538326081 = 4400556^2 + 1374241^2 .

It is a cyclic number.

It is not a de Polignac number, because 21253431435217 - 2¹⁵ = 21253431402449 is a prime.

It is not a weakly prime, because it can be changed into another prime (21253431435017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626715717608 + 10626715717609.

It is an arithmetic number, because the mean of its divisors is an integer number (10626715717609).

Almost surely, 2^{21253431435217} is an apocalyptic number.

It is an amenable number.

21253431435217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253431435217 is an equidigital number, since it uses as much as digits as its factorization.

21253431435217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 604800, while the sum is 43.

The spelling of 21253431435217 in words is "twenty-one trillion, two hundred fifty-three billion, four hundred thirty-one million, four hundred thirty-five thousand, two hundred seventeen".