21342123 has 40 divisors (see below), whose sum is σ = 36851760. Its totient is φ = 12165120.

The previous prime is 21342119. The next prime is 21342143. The reversal of 21342123 is 32124312.

It is not a de Polignac number, because 21342123 - 2² = 21342119 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21342096 and 21342105.

It is not an unprimeable number, because it can be changed into a prime (21342143) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 14443 + ... + 15851.

It is an arithmetic number, because the mean of its divisors is an integer number (921294).

Almost surely, 2^21342123 is an apocalyptic number.

21342123 is a deficient number, since it is larger than the sum of its proper divisors (15509637).

21342123 is a wasteful number, since it uses less digits than its factorization.

21342123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449 (or 1440 counting only the distinct ones).

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

The square root of 21342123 is about 4619.7535648560. The cubic root of 21342123 is about 277.3825946007.

Adding to 21342123 its reverse (32124312), we get a palindrome (53466435).

It can be divided in two parts, 213421 and 23, that added together give a square (213444 = 462²).

The spelling of 21342123 in words is "twenty-one million, three hundred forty-two thousand, one hundred twenty-three".