21801858563 has 2 divisors, whose sum is σ = 21801858564. Its totient is φ = 21801858562.

The previous prime is 21801858511. The next prime is 21801858599. The reversal of 21801858563 is 36585810812.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21801858563 - 2⁶ = 21801858499 is a prime.

It is not a weakly prime, because it can be changed into another prime (21801855563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10900929281 + 10900929282.

It is an arithmetic number, because the mean of its divisors is an integer number (10900929282).

Almost surely, 2^21801858563 is an apocalyptic number.

21801858563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21801858563 is an equidigital number, since it uses as much as digits as its factorization.

21801858563 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 460800, while the sum is 47.

The spelling of 21801858563 in words is "twenty-one billion, eight hundred one million, eight hundred fifty-eight thousand, five hundred sixty-three".