21146423221 has 16 divisors (see below), whose sum is σ = 26369435520. Its totient is φ = 16474567680.

The previous prime is 21146423209. The next prime is 21146423251. The reversal of 21146423221 is 12232464112.

It is a cyclic number.

It is not a de Polignac number, because 21146423221 - 2⁷ = 21146423093 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21146423221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21146423251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 427545 + ... + 474433.

It is an arithmetic number, because the mean of its divisors is an integer number (1648089720).

Almost surely, 2^21146423221 is an apocalyptic number.

It is an amenable number.

21146423221 is a deficient number, since it is larger than the sum of its proper divisors (5223012299).

21146423221 is a wasteful number, since it uses less digits than its factorization.

21146423221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52764.

The product of its digits is 4608, while the sum is 28.

Adding to 21146423221 its reverse (12232464112), we get a palindrome (33378887333).

The spelling of 21146423221 in words is "twenty-one billion, one hundred forty-six million, four hundred twenty-three thousand, two hundred twenty-one".