21420424121 has 8 divisors (see below), whose sum is σ = 21448169280. Its totient is φ = 21392698192.

The previous prime is 21420424061. The next prime is 21420424159. The reversal of 21420424121 is 12142402412.

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

It is a cyclic number.

It is not a de Polignac number, because 21420424121 - 2⁶ = 21420424057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420424321) 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, 4671596 + ... + 4676178.

It is an arithmetic number, because the mean of its divisors is an integer number (2681021160).

Almost surely, 2^21420424121 is an apocalyptic number.

It is an amenable number.

21420424121 is a deficient number, since it is larger than the sum of its proper divisors (27745159).

21420424121 is a wasteful number, since it uses less digits than its factorization.

21420424121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9615.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21420424121 its reverse (12142402412), we get a palindrome (33562826533).

The spelling of 21420424121 in words is "twenty-one billion, four hundred twenty million, four hundred twenty-four thousand, one hundred twenty-one".