21105234 has 48 divisors (see below), whose sum is σ = 47773440. Its totient is φ = 6726240.

The previous prime is 21105233. The next prime is 21105239. The reversal of 21105234 is 43250112.

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

It is not an unprimeable number, because it can be changed into a prime (21105233) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 60649 + ... + 60995.

It is an arithmetic number, because the mean of its divisors is an integer number (995280).

Almost surely, 2^21105234 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21105234, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23886720).

21105234 is an abundant number, since it is smaller than the sum of its proper divisors (26668206).

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

21105234 is a wasteful number, since it uses less digits than its factorization.

21105234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495 (or 492 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21105234 is about 4594.0433171663. The cubic root of 21105234 is about 276.3524954259.

Adding to 21105234 its reverse (43250112), we get a palindrome (64355346).

The spelling of 21105234 in words is "twenty-one million, one hundred five thousand, two hundred thirty-four".