21219391989 has 16 divisors (see below), whose sum is σ = 31724545600. Its totient is φ = 14016477168.

The previous prime is 21219391979. The next prime is 21219392009. The reversal of 21219391989 is 98919391212.

It is not a de Polignac number, because 21219391989 - 2²⁰ = 21218343413 is a prime.

It is a super-2 number, since 2×21219391989² (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 (21219391979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3602119 + ... + 3608004.

It is an arithmetic number, because the mean of its divisors is an integer number (1982784100).

Almost surely, 2^21219391989 is an apocalyptic number.

It is an amenable number.

21219391989 is a deficient number, since it is larger than the sum of its proper divisors (10505153611).

21219391989 is a wasteful number, since it uses less digits than its factorization.

21219391989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7210241 (or 7210235 counting only the distinct ones).

The product of its digits is 629856, while the sum is 54.

The spelling of 21219391989 in words is "twenty-one billion, two hundred nineteen million, three hundred ninety-one thousand, nine hundred eighty-nine".