21165682 has 4 divisors (see below), whose sum is σ = 31748526. Its totient is φ = 10582840.

The previous prime is 21165671. The next prime is 21165733. The reversal of 21165682 is 28656112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 16232841 + 4932841 = 4029^2 + 2221^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5291419 + ... + 5291422.

Almost surely, 2^21165682 is an apocalyptic number.

21165682 is a deficient number, since it is larger than the sum of its proper divisors (10582844).

21165682 is a wasteful number, since it uses less digits than its factorization.

21165682 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10582843.

The product of its digits is 5760, while the sum is 31.

The square root of 21165682 is about 4600.6175672403. The cubic root of 21165682 is about 276.6160798464.

The spelling of 21165682 in words is "twenty-one million, one hundred sixty-five thousand, six hundred eighty-two".