21009418 has 8 divisors (see below), whose sum is σ = 31913280. Its totient is φ = 10371660.

The previous prime is 21009407. The next prime is 21009449. The reversal of 21009418 is 81490012.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 21009392 and 21009401.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66328 + ... + 66643.

It is an arithmetic number, because the mean of its divisors is an integer number (3989160).

Almost surely, 2^21009418 is an apocalyptic number.

21009418 is a deficient number, since it is larger than the sum of its proper divisors (10903862).

21009418 is a wasteful number, since it uses less digits than its factorization.

21009418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133052.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21009418 is about 4583.6031678146. The cubic root of 21009418 is about 275.9336552009.

The spelling of 21009418 in words is "twenty-one million, nine thousand, four hundred eighteen".