21945219191 has 4 divisors (see below), whose sum is σ = 25080250512. Its totient is φ = 18810187872.

The previous prime is 21945219161. The next prime is 21945219211. The reversal of 21945219191 is 19191254912.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21945219191 - 2²² = 21941024887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945219161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1567515650 + ... + 1567515663.

It is an arithmetic number, because the mean of its divisors is an integer number (6270062628).

Almost surely, 2^21945219191 is an apocalyptic number.

21945219191 is a deficient number, since it is larger than the sum of its proper divisors (3135031321).

21945219191 is an equidigital number, since it uses as much as digits as its factorization.

21945219191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3135031320.

The product of its digits is 58320, while the sum is 44.

The spelling of 21945219191 in words is "twenty-one billion, nine hundred forty-five million, two hundred nineteen thousand, one hundred ninety-one".