21825509 has 8 divisors (see below), whose sum is σ = 23017440. Its totient is φ = 20637936.

The previous prime is 21825499. The next prime is 21825521. The reversal of 21825509 is 90552812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21825509 - 2⁸ = 21825253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21825589) 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 7 ways as a sum of consecutive naturals, for example, 17387 + ... + 18599.

It is an arithmetic number, because the mean of its divisors is an integer number (2877180).

Almost surely, 2^21825509 is an apocalyptic number.

It is an amenable number.

21825509 is a deficient number, since it is larger than the sum of its proper divisors (1191931).

21825509 is a wasteful number, since it uses less digits than its factorization.

21825509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2179.

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

The square root of 21825509 is about 4671.7779270851. Note that the first 3 decimals coincide. The cubic root of 21825509 is about 279.4611618424.

The spelling of 21825509 in words is "twenty-one million, eight hundred twenty-five thousand, five hundred nine".