21042825 has 24 divisors (see below), whose sum is σ = 35735808. Its totient is φ = 10918080.

The previous prime is 21042803. The next prime is 21042829. The reversal of 21042825 is 52824012.

It is not a de Polignac number, because 21042825 - 2¹¹ = 21040777 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21042795 and 21042804.

It is not an unprimeable number, because it can be changed into a prime (21042829) 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, 1017 + ... + 6566.

It is an arithmetic number, because the mean of its divisors is an integer number (1488992).

Almost surely, 2^21042825 is an apocalyptic number.

21042825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21042825 is a deficient number, since it is larger than the sum of its proper divisors (14692983).

21042825 is a wasteful number, since it uses less digits than its factorization.

21042825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7633 (or 7628 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21042825 is about 4587.2459057696. The cubic root of 21042825 is about 276.0798314543.

Adding to 21042825 its reverse (52824012), we get a palindrome (73866837).

The spelling of 21042825 in words is "twenty-one million, forty-two thousand, eight hundred twenty-five".