21800099999 has 4 divisors (see below), whose sum is σ = 21844499880. Its totient is φ = 21755700120.

The previous prime is 21800099983. The next prime is 21800100001. The reversal of 21800099999 is 99999000812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21800099999 - 2⁴ = 21800099983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21800099969) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22199204 + ... + 22200185.

It is an arithmetic number, because the mean of its divisors is an integer number (5461124970).

Almost surely, 2^21800099999 is an apocalyptic number.

21800099999 is a deficient number, since it is larger than the sum of its proper divisors (44399881).

21800099999 is an equidigital number, since it uses as much as digits as its factorization.

21800099999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44399880.

The product of its (nonzero) digits is 944784, while the sum is 56.

The spelling of 21800099999 in words is "twenty-one billion, eight hundred million, ninety-nine thousand, nine hundred ninety-nine".