21230001221 has 24 divisors (see below), whose sum is σ = 25300766016. Its totient is φ = 17657552640.

The previous prime is 21230001197. The next prime is 21230001257. The reversal of 21230001221 is 12210003212.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21230001221 is a prime.

It is a super-2 number, since 2×21230001221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21230001196 and 21230001205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21230001521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 159536 + ... + 260598.

It is an arithmetic number, because the mean of its divisors is an integer number (1054198584).

Almost surely, 2^21230001221 is an apocalyptic number.

It is an amenable number.

21230001221 is a deficient number, since it is larger than the sum of its proper divisors (4070764795).

21230001221 is a wasteful number, since it uses less digits than its factorization.

21230001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101213 (or 101200 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21230001221 its reverse (12210003212), we get a palindrome (33440004433).

The spelling of 21230001221 in words is "twenty-one billion, two hundred thirty million, one thousand, two hundred twenty-one".