21108802191 has 8 divisors (see below), whose sum is σ = 29626389120. Its totient is φ = 13331875032.

The previous prime is 21108802163. The next prime is 21108802219. The reversal of 21108802191 is 19120880112.

It is an interprime number because it is at equal distance from previous prime (21108802163) and next prime (21108802219).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21108802191 - 2¹⁰ = 21108801167 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108802591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185164875 + ... + 185164988.

It is an arithmetic number, because the mean of its divisors is an integer number (3703298640).

Almost surely, 2^21108802191 is an apocalyptic number.

21108802191 is a deficient number, since it is larger than the sum of its proper divisors (8517586929).

21108802191 is a wasteful number, since it uses less digits than its factorization.

21108802191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370329885.

The product of its (nonzero) digits is 2304, while the sum is 33.

The spelling of 21108802191 in words is "twenty-one billion, one hundred eight million, eight hundred two thousand, one hundred ninety-one".