21059825 has 6 divisors (see below), whose sum is σ = 26114214. Its totient is φ = 16847840.

The previous prime is 21059791. The next prime is 21059827. The reversal of 21059825 is 52895012.

It can be written as a sum of positive squares in 3 ways, for example, as 3352561 + 17707264 = 1831^2 + 4208^2 .

It is not a de Polignac number, because 21059825 - 2⁶ = 21059761 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21059791 and 21059800.

It is not an unprimeable number, because it can be changed into a prime (21059827) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 421172 + ... + 421221.

It is an arithmetic number, because the mean of its divisors is an integer number (4352369).

Almost surely, 2^21059825 is an apocalyptic number.

21059825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21059825 is a deficient number, since it is larger than the sum of its proper divisors (5054389).

21059825 is an equidigital number, since it uses as much as digits as its factorization.

21059825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 842403 (or 842398 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 21059825 is about 4589.0984953474. The cubic root of 21059825 is about 276.1541575618.

The spelling of 21059825 in words is "twenty-one million, fifty-nine thousand, eight hundred twenty-five".