21810224 has 10 divisors (see below), whose sum is σ = 42257340. Its totient is φ = 10905104.

The previous prime is 21810221. The next prime is 21810253. The reversal of 21810224 is 42201812.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21810196 and 21810205.

It is not an unprimeable number, because it can be changed into a prime (21810221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 681554 + ... + 681585.

It is an arithmetic number, because the mean of its divisors is an integer number (4225734).

Almost surely, 2^21810224 is an apocalyptic number.

It is an amenable number.

21810224 is a deficient number, since it is larger than the sum of its proper divisors (20447116).

21810224 is a wasteful number, since it uses less digits than its factorization.

21810224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1363147 (or 1363141 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21810224 is about 4670.1417537372. The cubic root of 21810224 is about 279.3959085126.

The spelling of 21810224 in words is "twenty-one million, eight hundred ten thousand, two hundred twenty-four".