21085284851 has 2 divisors, whose sum is σ = 21085284852. Its totient is φ = 21085284850.

The previous prime is 21085284793. The next prime is 21085284917. The reversal of 21085284851 is 15848258012.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21085284851 is a prime.

It is not a weakly prime, because it can be changed into another prime (21085284251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542642425 + 10542642426.

It is an arithmetic number, because the mean of its divisors is an integer number (10542642426).

Almost surely, 2^21085284851 is an apocalyptic number.

21085284851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085284851 is an equidigital number, since it uses as much as digits as its factorization.

21085284851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 204800, while the sum is 44.

The spelling of 21085284851 in words is "twenty-one billion, eighty-five million, two hundred eighty-four thousand, eight hundred fifty-one".