21128985847 has 2 divisors, whose sum is σ = 21128985848. Its totient is φ = 21128985846.

The previous prime is 21128985841. The next prime is 21128985881. The reversal of 21128985847 is 74858982112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21128985847 - 2¹⁹ = 21128461559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21128985841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10564492923 + 10564492924.

It is an arithmetic number, because the mean of its divisors is an integer number (10564492924).

Almost surely, 2^21128985847 is an apocalyptic number.

21128985847 is a deficient number, since it is larger than the sum of its proper divisors (1).

21128985847 is an equidigital number, since it uses as much as digits as its factorization.

21128985847 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2580480, while the sum is 55.

The spelling of 21128985847 in words is "twenty-one billion, one hundred twenty-eight million, nine hundred eighty-five thousand, eight hundred forty-seven".