21004825 has 12 divisors (see below), whose sum is σ = 26887168. Its totient is φ = 16261200.

The previous prime is 21004813. The next prime is 21004829. The reversal of 21004825 is 52840012.

It is not a de Polignac number, because 21004825 - 2¹¹ = 21002777 is a prime.

It is a hoax number, since the sum of its digits (22) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 21004796 and 21004805.

It is not an unprimeable number, because it can be changed into a prime (21004829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12777 + ... + 14326.

Almost surely, 2^21004825 is an apocalyptic number.

21004825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21004825 is a deficient number, since it is larger than the sum of its proper divisors (5882343).

21004825 is a wasteful number, since it uses less digits than its factorization.

21004825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27144 (or 27139 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 21004825 is about 4583.1021153799. The cubic root of 21004825 is about 275.9135458758.

Adding to 21004825 its reverse (52840012), we get a palindrome (73844837).

The spelling of 21004825 in words is "twenty-one million, four thousand, eight hundred twenty-five".