21000111009 has 4 divisors (see below), whose sum is σ = 28000148016. Its totient is φ = 14000074004.

The previous prime is 21000110993. The next prime is 21000111017. The reversal of 21000111009 is 90011100012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21000111009 - 2⁴ = 21000110993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000111049) 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, 3500018499 + ... + 3500018504.

It is an arithmetic number, because the mean of its divisors is an integer number (7000037004).

Almost surely, 2^21000111009 is an apocalyptic number.

It is an amenable number.

21000111009 is a deficient number, since it is larger than the sum of its proper divisors (7000037007).

21000111009 is an equidigital number, since it uses as much as digits as its factorization.

21000111009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7000037006.

The product of its (nonzero) digits is 18, while the sum is 15.

The spelling of 21000111009 in words is "twenty-one billion, one hundred eleven thousand, nine".