21240786571 has 2 divisors, whose sum is σ = 21240786572. Its totient is φ = 21240786570.

The previous prime is 21240786559. The next prime is 21240786617. The reversal of 21240786571 is 17568704212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21240786571 - 2⁷ = 21240786443 is a prime.

It is not a weakly prime, because it can be changed into another prime (21240786551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620393285 + 10620393286.

It is an arithmetic number, because the mean of its divisors is an integer number (10620393286).

Almost surely, 2^21240786571 is an apocalyptic number.

21240786571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240786571 is an equidigital number, since it uses as much as digits as its factorization.

21240786571 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 188160, while the sum is 43.

The spelling of 21240786571 in words is "twenty-one billion, two hundred forty million, seven hundred eighty-six thousand, five hundred seventy-one".