21420230221 has 4 divisors (see below), whose sum is σ = 23067940252. Its totient is φ = 19772520192.

The previous prime is 21420230189. The next prime is 21420230263. The reversal of 21420230221 is 12203202412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8106301225 + 13313928996 = 90035^2 + 115386^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420230221 - 2⁵ = 21420230189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420230021) 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, 823854996 + ... + 823855021.

It is an arithmetic number, because the mean of its divisors is an integer number (5766985063).

Almost surely, 2^21420230221 is an apocalyptic number.

It is an amenable number.

21420230221 is a deficient number, since it is larger than the sum of its proper divisors (1647710031).

21420230221 is a wasteful number, since it uses less digits than its factorization.

21420230221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1647710030.

The product of its (nonzero) digits is 384, while the sum is 19.

Adding to 21420230221 its reverse (12203202412), we get a palindrome (33623432633).

The spelling of 21420230221 in words is "twenty-one billion, four hundred twenty million, two hundred thirty thousand, two hundred twenty-one".