21123342 has 40 divisors (see below), whose sum is σ = 47837592. Its totient is φ = 6966000.

The previous prime is 21123331. The next prime is 21123359. The reversal of 21123342 is 24332112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 15717 + ... + 17007.

Almost surely, 2^21123342 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21123342, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23918796).

21123342 is an abundant number, since it is smaller than the sum of its proper divisors (26714250).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123342 is a wasteful number, since it uses less digits than its factorization.

21123342 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1406 (or 1397 counting only the distinct ones).

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

The square root of 21123342 is about 4596.0137075514. The cubic root of 21123342 is about 276.4315083775.

Adding to 21123342 its reverse (24332112), we get a palindrome (45455454).

The spelling of 21123342 in words is "twenty-one million, one hundred twenty-three thousand, three hundred forty-two".