21123432321 has 8 divisors (see below), whose sum is σ = 28367199840. Its totient is φ = 13980976512.

The previous prime is 21123432307. The next prime is 21123432329. The reversal of 21123432321 is 12323432112.

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

It is not a de Polignac number, because 21123432321 - 2¹⁰ = 21123431297 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21123432291 and 21123432300.

It is not an unprimeable number, because it can be changed into a prime (21123432329) 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, 25327440 + ... + 25328273.

It is an arithmetic number, because the mean of its divisors is an integer number (3545899980).

Almost surely, 2^21123432321 is an apocalyptic number.

It is an amenable number.

21123432321 is a deficient number, since it is larger than the sum of its proper divisors (7243767519).

21123432321 is a wasteful number, since it uses less digits than its factorization.

21123432321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50655855.

The product of its digits is 1728, while the sum is 24.

Adding to 21123432321 its reverse (12323432112), we get a palindrome (33446864433).

The spelling of 21123432321 in words is "twenty-one billion, one hundred twenty-three million, four hundred thirty-two thousand, three hundred twenty-one".