21998121323 has 4 divisors (see below), whose sum is σ = 22326451560. Its totient is φ = 21669791088.

The previous prime is 21998121293. The next prime is 21998121443. The reversal of 21998121323 is 32312189912.

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 21998121323 - 2¹⁶ = 21998055787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21998127323) 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, 164165018 + ... + 164165151.

It is an arithmetic number, because the mean of its divisors is an integer number (5581612890).

Almost surely, 2^21998121323 is an apocalyptic number.

21998121323 is a deficient number, since it is larger than the sum of its proper divisors (328330237).

21998121323 is an equidigital number, since it uses as much as digits as its factorization.

21998121323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328330236.

The product of its digits is 46656, while the sum is 41.

The spelling of 21998121323 in words is "twenty-one billion, nine hundred ninety-eight million, one hundred twenty-one thousand, three hundred twenty-three".