21111101209 has 4 divisors (see below), whose sum is σ = 23030292240. Its totient is φ = 19191910180.

The previous prime is 21111101201. The next prime is 21111101213. The reversal of 21111101209 is 90210111112.

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 21111101209 - 2³ = 21111101201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111101201) 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, 959595499 + ... + 959595520.

It is an arithmetic number, because the mean of its divisors is an integer number (5757573060).

Almost surely, 2^21111101209 is an apocalyptic number.

It is an amenable number.

21111101209 is a deficient number, since it is larger than the sum of its proper divisors (1919191031).

21111101209 is a wasteful number, since it uses less digits than its factorization.

21111101209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1919191030.

The product of its (nonzero) digits is 36, while the sum is 19.

The spelling of 21111101209 in words is "twenty-one billion, one hundred eleven million, one hundred one thousand, two hundred nine".