21558733771 has 2 divisors, whose sum is σ = 21558733772. Its totient is φ = 21558733770.

The previous prime is 21558733717. The next prime is 21558733793. The reversal of 21558733771 is 17733785512.

Together with previous prime (21558733717) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21558733771 - 2¹⁹ = 21558209483 is a prime.

It is not a weakly prime, because it can be changed into another prime (21558733711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10779366885 + 10779366886.

It is an arithmetic number, because the mean of its divisors is an integer number (10779366886).

Almost surely, 2^21558733771 is an apocalyptic number.

21558733771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21558733771 is an equidigital number, since it uses as much as digits as its factorization.

21558733771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1234800, while the sum is 49.

The spelling of 21558733771 in words is "twenty-one billion, five hundred fifty-eight million, seven hundred thirty-three thousand, seven hundred seventy-one".