21432240221 has 16 divisors (see below), whose sum is σ = 25944906240. Its totient is φ = 17283144960.

The previous prime is 21432240211. The next prime is 21432240233. The reversal of 21432240221 is 12204223412.

It is a cyclic number.

It is not a de Polignac number, because 21432240221 - 2⁶ = 21432240157 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 (21432240211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 284135 + ... + 351563.

It is an arithmetic number, because the mean of its divisors is an integer number (1621556640).

Almost surely, 2^21432240221 is an apocalyptic number.

It is an amenable number.

21432240221 is a deficient number, since it is larger than the sum of its proper divisors (4512666019).

21432240221 is a wasteful number, since it uses less digits than its factorization.

21432240221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70124.

The product of its (nonzero) digits is 1536, while the sum is 23.

Adding to 21432240221 its reverse (12204223412), we get a palindrome (33636463633).

The spelling of 21432240221 in words is "twenty-one billion, four hundred thirty-two million, two hundred forty thousand, two hundred twenty-one".