21825081 has 12 divisors (see below), whose sum is σ = 32612580. Its totient is φ = 14048160.

The previous prime is 21825071. The next prime is 21825109. The reversal of 21825081 is 18052812.

It can be written as a sum of positive squares in 2 ways, for example, as 18275625 + 3549456 = 4275^2 + 1884^2 .

It is not a de Polignac number, because 21825081 - 2⁶ = 21825017 is a prime.

It is a super-2 number, since 2×21825081² = 952668321313122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21825031) 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 11 ways as a sum of consecutive naturals, for example, 41550 + ... + 42071.

It is an arithmetic number, because the mean of its divisors is an integer number (2717715).

Almost surely, 2^21825081 is an apocalyptic number.

It is an amenable number.

21825081 is a deficient number, since it is larger than the sum of its proper divisors (10787499).

21825081 is a wasteful number, since it uses less digits than its factorization.

21825081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83656 (or 83653 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21825081 is about 4671.7321198887. The cubic root of 21825081 is about 279.4593350785.

Adding to 21825081 its reverse (18052812), we get a palindrome (39877893).

The spelling of 21825081 in words is "twenty-one million, eight hundred twenty-five thousand, eighty-one".