21873638317 has 2 divisors, whose sum is σ = 21873638318. Its totient is φ = 21873638316.

The previous prime is 21873638291. The next prime is 21873638333. The reversal of 21873638317 is 71383637812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20952273001 + 921365316 = 144749^2 + 30354^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21873638317 is a prime.

It is a super-3 number, since 3×21873638317³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21873638357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936819158 + 10936819159.

It is an arithmetic number, because the mean of its divisors is an integer number (10936819159).

Almost surely, 2^21873638317 is an apocalyptic number.

It is an amenable number.

21873638317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21873638317 is an equidigital number, since it uses as much as digits as its factorization.

21873638317 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1016064, while the sum is 49.

The spelling of 21873638317 in words is "twenty-one billion, eight hundred seventy-three million, six hundred thirty-eight thousand, three hundred seventeen".