21873638417 has 2 divisors, whose sum is σ = 21873638418. Its totient is φ = 21873638416.

The previous prime is 21873638407. The next prime is 21873638447. The reversal of 21873638417 is 71483637812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16199180176 + 5674458241 = 127276^2 + 75329^2 .

It is a cyclic number.

It is not a de Polignac number, because 21873638417 - 2⁴ = 21873638401 is a prime.

It is not a weakly prime, because it can be changed into another prime (21873638407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936819208 + 10936819209.

It is an arithmetic number, because the mean of its divisors is an integer number (10936819209).

Almost surely, 2^21873638417 is an apocalyptic number.

It is an amenable number.

21873638417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21873638417 is an equidigital number, since it uses as much as digits as its factorization.

21873638417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1354752, while the sum is 50.

The spelling of 21873638417 in words is "twenty-one billion, eight hundred seventy-three million, six hundred thirty-eight thousand, four hundred seventeen".