21223725 has 24 divisors (see below), whose sum is σ = 35911392. Its totient is φ = 11054400.

The previous prime is 21223723. The next prime is 21223739. The reversal of 21223725 is 52732212.

It is a happy number.

It is not a de Polignac number, because 21223725 - 2¹ = 21223723 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21223695 and 21223704.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21223723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66 + ... + 6515.

It is an arithmetic number, because the mean of its divisors is an integer number (1496308).

Almost surely, 2^21223725 is an apocalyptic number.

21223725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21223725 is a deficient number, since it is larger than the sum of its proper divisors (14687667).

21223725 is a wasteful number, since it uses less digits than its factorization.

21223725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6637 (or 6632 counting only the distinct ones).

The product of its digits is 1680, while the sum is 24.

The square root of 21223725 is about 4606.9214232500. The cubic root of 21223725 is about 276.8687053450.

Adding to 21223725 its reverse (52732212), we get a palindrome (73955937).

The spelling of 21223725 in words is "twenty-one million, two hundred twenty-three thousand, seven hundred twenty-five".