21820125 has 32 divisors (see below), whose sum is σ = 37499904. Its totient is φ = 11256000.

The previous prime is 21820111. The next prime is 21820133. The reversal of 21820125 is 52102812.

It is a happy number.

It is not a de Polignac number, because 21820125 - 2⁸ = 21819869 is a prime.

It is a super-3 number, since 3×21820125³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10687 + ... + 12563.

It is an arithmetic number, because the mean of its divisors is an integer number (1171872).

Almost surely, 2^21820125 is an apocalyptic number.

21820125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21820125 is a deficient number, since it is larger than the sum of its proper divisors (15679779).

21820125 is a wasteful number, since it uses less digits than its factorization.

21820125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1926 (or 1916 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21820125 is about 4671.2016655246. The cubic root of 21820125 is about 279.4381804367.

Adding to 21820125 its reverse (52102812), we get a palindrome (73922937).

It can be divided in two parts, 21820 and 125, that added together give a triangular number (21945 = T₂₀₉).

The spelling of 21820125 in words is "twenty-one million, eight hundred twenty thousand, one hundred twenty-five".