21390382 has 16 divisors (see below), whose sum is σ = 35122752. Its totient is φ = 9709920.

The previous prime is 21390379. The next prime is 21390389. The reversal of 21390382 is 28309312.

It is a self number, because there is not a number n which added to its sum of digits gives 21390382.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390389) 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 7 ways as a sum of consecutive naturals, for example, 5158 + ... + 8329.

It is an arithmetic number, because the mean of its divisors is an integer number (2195172).

Almost surely, 2^21390382 is an apocalyptic number.

21390382 is a deficient number, since it is larger than the sum of its proper divisors (13732370).

21390382 is a wasteful number, since it uses less digits than its factorization.

21390382 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13563.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21390382 is about 4624.9737296551. The cubic root of 21390382 is about 277.5915105494.

Adding to 21390382 its reverse (28309312), we get a palindrome (49699694).

The spelling of 21390382 in words is "twenty-one million, three hundred ninety thousand, three hundred eighty-two".