21853459891 has 2 divisors, whose sum is σ = 21853459892. Its totient is φ = 21853459890.

The previous prime is 21853459853. The next prime is 21853459939. The reversal of 21853459891 is 19895435812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21853459891 is a prime.

It is not a weakly prime, because it can be changed into another prime (21853459091) 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, 10926729945 + 10926729946.

It is an arithmetic number, because the mean of its divisors is an integer number (10926729946).

Almost surely, 2^21853459891 is an apocalyptic number.

21853459891 is a deficient number, since it is larger than the sum of its proper divisors (1).

21853459891 is an equidigital number, since it uses as much as digits as its factorization.

21853459891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3110400, while the sum is 55.

The spelling of 21853459891 in words is "twenty-one billion, eight hundred fifty-three million, four hundred fifty-nine thousand, eight hundred ninety-one".