21081982 has 8 divisors (see below), whose sum is σ = 33287400. Its totient is φ = 9986184.

The previous prime is 21081979. The next prime is 21082003. The reversal of 21081982 is 28918012.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 277357 + ... + 277432.

It is an arithmetic number, because the mean of its divisors is an integer number (4160925).

Almost surely, 2^21081982 is an apocalyptic number.

21081982 is a deficient number, since it is larger than the sum of its proper divisors (12205418).

21081982 is a wasteful number, since it uses less digits than its factorization.

21081982 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 554810.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21081982 is about 4591.5119514164. The cubic root of 21081982 is about 276.2509706974.

Adding to 21081982 its reverse (28918012), we get a palindrome (49999994).

The spelling of 21081982 in words is "twenty-one million, eighty-one thousand, nine hundred eighty-two".