21748810871 has 2 divisors, whose sum is σ = 21748810872. Its totient is φ = 21748810870.

The previous prime is 21748810859. The next prime is 21748810873. The reversal of 21748810871 is 17801884712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21748810871 - 2¹⁰ = 21748809847 is a prime.

It is a Sophie Germain prime.

Together with 21748810873, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21748810873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10874405435 + 10874405436.

It is an arithmetic number, because the mean of its divisors is an integer number (10874405436).

Almost surely, 2^21748810871 is an apocalyptic number.

21748810871 is a deficient number, since it is larger than the sum of its proper divisors (1).

21748810871 is an equidigital number, since it uses as much as digits as its factorization.

21748810871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 200704, while the sum is 47.

The spelling of 21748810871 in words is "twenty-one billion, seven hundred forty-eight million, eight hundred ten thousand, eight hundred seventy-one".