21603042 has 48 divisors (see below), whose sum is σ = 48609600. Its totient is φ = 6928416.

The previous prime is 21603017. The next prime is 21603047. The reversal of 21603042 is 24030612.

It is a happy number.

21603042 is a `hidden beast` number, since 21 + 603 + 0 + 42 = 666.

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 (21603047) 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, 108459 + ... + 108657.

It is an arithmetic number, because the mean of its divisors is an integer number (1012700).

Almost surely, 2^21603042 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21603042, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24304800).

21603042 is an abundant number, since it is smaller than the sum of its proper divisors (27006558).

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

21603042 is a wasteful number, since it uses less digits than its factorization.

21603042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407 (or 404 counting only the distinct ones).

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

The square root of 21603042 is about 4647.9072710199. The cubic root of 21603042 is about 278.5084032116.

Adding to 21603042 its reverse (24030612), we get a palindrome (45633654).

The spelling of 21603042 in words is "twenty-one million, six hundred three thousand, forty-two".