21185825 has 24 divisors (see below), whose sum is σ = 28212480. Its totient is φ = 15724800.

The previous prime is 21185821. The next prime is 21185837. The reversal of 21185825 is 52858112.

It is a happy number.

It is not a de Polignac number, because 21185825 - 2² = 21185821 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21185791 and 21185800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185821) 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, 33260 + ... + 33890.

It is an arithmetic number, because the mean of its divisors is an integer number (1175520).

Almost surely, 2^21185825 is an apocalyptic number.

21185825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21185825 is a deficient number, since it is larger than the sum of its proper divisors (7026655).

21185825 is a wasteful number, since it uses less digits than its factorization.

21185825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737 (or 732 counting only the distinct ones).

The product of its digits is 6400, while the sum is 32.

The square root of 21185825 is about 4602.8062092597. The cubic root of 21185825 is about 276.7038022119.

The spelling of 21185825 in words is "twenty-one million, one hundred eighty-five thousand, eight hundred twenty-five".