21123420321 has 8 divisors (see below), whose sum is σ = 28167137920. Its totient is φ = 14080991472.

The previous prime is 21123420217. The next prime is 21123420371. The reversal of 21123420321 is 12302432112.

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

It is not a de Polignac number, because 21123420321 - 2¹⁷ = 21123289249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123420371) 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, 283270 + ... + 349983.

It is an arithmetic number, because the mean of its divisors is an integer number (3520892240).

Almost surely, 2^21123420321 is an apocalyptic number.

It is an amenable number.

21123420321 is a deficient number, since it is larger than the sum of its proper divisors (7043717599).

21123420321 is a wasteful number, since it uses less digits than its factorization.

21123420321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 644375.

The product of its (nonzero) digits is 576, while the sum is 21.

Adding to 21123420321 its reverse (12302432112), we get a palindrome (33425852433).

The spelling of 21123420321 in words is "twenty-one billion, one hundred twenty-three million, four hundred twenty thousand, three hundred twenty-one".