21250640317 has 2 divisors, whose sum is σ = 21250640318. Its totient is φ = 21250640316.

The previous prime is 21250640287. The next prime is 21250640351. The reversal of 21250640317 is 71304605212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18990493636 + 2260146681 = 137806^2 + 47541^2 .

It is a cyclic number.

It is not a de Polignac number, because 21250640317 - 2⁷ = 21250640189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21250640017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625320158 + 10625320159.

It is an arithmetic number, because the mean of its divisors is an integer number (10625320159).

Almost surely, 2^21250640317 is an apocalyptic number.

It is an amenable number.

21250640317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21250640317 is an equidigital number, since it uses as much as digits as its factorization.

21250640317 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 31.

The spelling of 21250640317 in words is "twenty-one billion, two hundred fifty million, six hundred forty thousand, three hundred seventeen".