21845125 has 8 divisors (see below), whose sum is σ = 27262872. Its totient is φ = 17476000.

The previous prime is 21845113. The next prime is 21845179. The reversal of 21845125 is 52154812.

It can be written as a sum of positive squares in 4 ways, for example, as 5377761 + 16467364 = 2319^2 + 4058^2 .

It is not a de Polignac number, because 21845125 - 2¹⁷ = 21714053 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21845093 and 21845102.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 87256 + ... + 87505.

It is an arithmetic number, because the mean of its divisors is an integer number (3407859).

Almost surely, 2^21845125 is an apocalyptic number.

21845125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21845125 is a deficient number, since it is larger than the sum of its proper divisors (5417747).

21845125 is an equidigital number, since it uses as much as digits as its factorization.

21845125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174776 (or 174766 counting only the distinct ones).

The product of its digits is 3200, while the sum is 28.

The square root of 21845125 is about 4673.8768704364. The cubic root of 21845125 is about 279.5448600608.

Adding to 21845125 its reverse (52154812), we get a palindrome (73999937).

The spelling of 21845125 in words is "twenty-one million, eight hundred forty-five thousand, one hundred twenty-five".