21939916819 has 4 divisors (see below), whose sum is σ = 21968448040. Its totient is φ = 21911385600.

The previous prime is 21939916793. The next prime is 21939916841. The reversal of 21939916819 is 91861993912.

It is a happy number.

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 21939916819 - 2¹¹ = 21939914771 is a prime.

It is a super-2 number, since 2×21939916819² (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 (21939916849) 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, 14264457 + ... + 14265994.

It is an arithmetic number, because the mean of its divisors is an integer number (5492112010).

Almost surely, 2^21939916819 is an apocalyptic number.

21939916819 is a deficient number, since it is larger than the sum of its proper divisors (28531221).

21939916819 is an equidigital number, since it uses as much as digits as its factorization.

21939916819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28531220.

The product of its digits is 1889568, while the sum is 58.

The spelling of 21939916819 in words is "twenty-one billion, nine hundred thirty-nine million, nine hundred sixteen thousand, eight hundred nineteen".