21321423 has 12 divisors (see below), whose sum is σ = 31379400. Its totient is φ = 13945776.

The previous prime is 21321407. The next prime is 21321431. The reversal of 21321423 is 32412312.

It is not a de Polignac number, because 21321423 - 2⁴ = 21321407 is a prime.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21321396 and 21321405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321493) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21873 + ... + 22826.

It is an arithmetic number, because the mean of its divisors is an integer number (2614950).

It is a self-describing number.

Almost surely, 2^21321423 is an apocalyptic number.

21321423 is a deficient number, since it is larger than the sum of its proper divisors (10057977).

21321423 is a wasteful number, since it uses less digits than its factorization.

21321423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44758 (or 44755 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21321423 is about 4617.5126421051. The cubic root of 21321423 is about 277.2928866077.

Adding to 21321423 its reverse (32412312), we get a palindrome (53733735).

The spelling of 21321423 in words is "twenty-one million, three hundred twenty-one thousand, four hundred twenty-three".