21042872 has 16 divisors (see below), whose sum is σ = 41776560. Its totient is φ = 9902464.

The previous prime is 21042863. The next prime is 21042877. The reversal of 21042872 is 27824012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042877) 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, 77228 + ... + 77499.

It is an arithmetic number, because the mean of its divisors is an integer number (2611035).

Almost surely, 2^21042872 is an apocalyptic number.

It is an amenable number.

21042872 is a deficient number, since it is larger than the sum of its proper divisors (20733688).

21042872 is a wasteful number, since it uses less digits than its factorization.

21042872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154750 (or 154746 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 21042872 is about 4587.2510286663. The cubic root of 21042872 is about 276.0800369993.

Adding to 21042872 its reverse (27824012), we get a palindrome (48866884).

The spelling of 21042872 in words is "twenty-one million, forty-two thousand, eight hundred seventy-two".