21738847771 has 2 divisors, whose sum is σ = 21738847772. Its totient is φ = 21738847770.

The previous prime is 21738847657. The next prime is 21738847829. The reversal of 21738847771 is 17774883712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21738847771 - 2⁷ = 21738847643 is a prime.

It is not a weakly prime, because it can be changed into another prime (21738847271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10869423885 + 10869423886.

It is an arithmetic number, because the mean of its divisors is an integer number (10869423886).

Almost surely, 2^21738847771 is an apocalyptic number.

21738847771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21738847771 is an equidigital number, since it uses as much as digits as its factorization.

21738847771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3687936, while the sum is 55.

The spelling of 21738847771 in words is "twenty-one billion, seven hundred thirty-eight million, eight hundred forty-seven thousand, seven hundred seventy-one".