21042444 has 12 divisors (see below), whose sum is σ = 49099064. Its totient is φ = 7014144.

The previous prime is 21042419. The next prime is 21042449. The reversal of 21042444 is 44424012.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21042444.

It is not an unprimeable number, because it can be changed into a prime (21042449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 876757 + ... + 876780.

Almost surely, 2^21042444 is an apocalyptic number.

It is an amenable number.

21042444 is an abundant number, since it is smaller than the sum of its proper divisors (28056620).

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

21042444 is a wasteful number, since it uses less digits than its factorization.

21042444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1753544 (or 1753542 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 21.

The square root of 21042444 is about 4587.2043773959. The cubic root of 21042444 is about 276.0781652165.

Adding to 21042444 its reverse (44424012), we get a palindrome (65466456).

The spelling of 21042444 in words is "twenty-one million, forty-two thousand, four hundred forty-four".