21201111091 has 4 divisors (see below), whose sum is σ = 21411023184. Its totient is φ = 20991199000.

The previous prime is 21201111089. The next prime is 21201111101. The reversal of 21201111091 is 19011110212.

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 21201111091 - 2¹ = 21201111089 is a prime.

It is a super-2 number, since 2×21201111091² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21201111011) 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, 104955895 + ... + 104956096.

It is an arithmetic number, because the mean of its divisors is an integer number (5352755796).

Almost surely, 2^21201111091 is an apocalyptic number.

21201111091 is a deficient number, since it is larger than the sum of its proper divisors (209912093).

21201111091 is a wasteful number, since it uses less digits than its factorization.

21201111091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209912092.

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

The spelling of 21201111091 in words is "twenty-one billion, two hundred one million, one hundred eleven thousand, ninety-one".