21201102191 has 4 divisors (see below), whose sum is σ = 21201577800. Its totient is φ = 21200626584.

The previous prime is 21201102137. The next prime is 21201102229. The reversal of 21201102191 is 19120110212.

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 21201102191 - 2¹⁰ = 21201101167 is a prime.

It is a super-2 number, since 2×21201102191² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201102121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 163121 + ... + 262698.

It is an arithmetic number, because the mean of its divisors is an integer number (5300394450).

Almost surely, 2^21201102191 is an apocalyptic number.

21201102191 is a deficient number, since it is larger than the sum of its proper divisors (475609).

21201102191 is an equidigital number, since it uses as much as digits as its factorization.

21201102191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475608.

The product of its (nonzero) digits is 72, while the sum is 20.

The spelling of 21201102191 in words is "twenty-one billion, two hundred one million, one hundred two thousand, one hundred ninety-one".