21009382 has 24 divisors (see below), whose sum is σ = 34532568. Its totient is φ = 9552960.

The previous prime is 21009379. The next prime is 21009389. The reversal of 21009382 is 28390012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21009389) 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, 32353 + ... + 32995.

It is an arithmetic number, because the mean of its divisors is an integer number (1438857).

Almost surely, 2^21009382 is an apocalyptic number.

21009382 is a deficient number, since it is larger than the sum of its proper divisors (13523186).

21009382 is a wasteful number, since it uses less digits than its factorization.

21009382 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 693 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21009382 is about 4583.5992407714. The cubic root of 21009382 is about 275.9334975951.

Adding to 21009382 its reverse (28390012), we get a palindrome (49399394).

The spelling of 21009382 in words is "twenty-one million, nine thousand, three hundred eighty-two".