21012782 has 16 divisors (see below), whose sum is σ = 38141280. Its totient is φ = 8475648.

The previous prime is 21012779. The next prime is 21012821. The reversal of 21012782 is 28721012.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43907 + ... + 44382.

It is an arithmetic number, because the mean of its divisors is an integer number (2383830).

Almost surely, 2^21012782 is an apocalyptic number.

21012782 is a deficient number, since it is larger than the sum of its proper divisors (17128498).

21012782 is a wasteful number, since it uses less digits than its factorization.

21012782 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88315.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21012782 is about 4583.9701133406. The cubic root of 21012782 is about 275.9483817912.

Adding to 21012782 its reverse (28721012), we get a palindrome (49733794).

The spelling of 21012782 in words is "twenty-one million, twelve thousand, seven hundred eighty-two".