21189042 has 48 divisors (see below), whose sum is σ = 52782912. Its totient is φ = 6017760.

The previous prime is 21189041. The next prime is 21189071. The reversal of 21189042 is 24098112.

It is a junction number, because it is equal to n+sod(n) for n = 21188997 and 21189015.

It is not an unprimeable number, because it can be changed into a prime (21189041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26188 + ... + 26984.

It is an arithmetic number, because the mean of its divisors is an integer number (1099644).

Almost surely, 2^21189042 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21189042, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26391456).

21189042 is an abundant number, since it is smaller than the sum of its proper divisors (31593870).

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

21189042 is a wasteful number, since it uses less digits than its factorization.

21189042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023 (or 1020 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21189042 is about 4603.1556567207. The cubic root of 21189042 is about 276.7178070332.

It can be divided in two parts, 211 and 89042, that added together give a triangular number (89253 = T₄₂₂).

The spelling of 21189042 in words is "twenty-one million, one hundred eighty-nine thousand, forty-two".