21112123009 has 4 divisors (see below), whose sum is σ = 21112482816. Its totient is φ = 21111763204.

The previous prime is 21112123007. The next prime is 21112123051. The reversal of 21112123009 is 90032121112.

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 21112123009 - 2¹ = 21112123007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112123007) 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, 69169 + ... + 216814.

It is an arithmetic number, because the mean of its divisors is an integer number (5278120704).

Almost surely, 2^21112123009 is an apocalyptic number.

It is an amenable number.

21112123009 is a deficient number, since it is larger than the sum of its proper divisors (359807).

21112123009 is an equidigital number, since it uses as much as digits as its factorization.

21112123009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359806.

The product of its (nonzero) digits is 216, while the sum is 22.

The spelling of 21112123009 in words is "twenty-one billion, one hundred twelve million, one hundred twenty-three thousand, nine".