21679165 has 8 divisors (see below), whose sum is σ = 27545400. Its totient is φ = 16323072.

The previous prime is 21679159. The next prime is 21679169. The reversal of 21679165 is 56197612.

It can be written as a sum of positive squares in 4 ways, for example, as 5846724 + 15832441 = 2418^2 + 3979^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21679165 - 2¹³ = 21670973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21679169) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 127440 + ... + 127609.

It is an arithmetic number, because the mean of its divisors is an integer number (3443175).

Almost surely, 2^21679165 is an apocalyptic number.

It is an amenable number.

21679165 is a deficient number, since it is larger than the sum of its proper divisors (5866235).

21679165 is a wasteful number, since it uses less digits than its factorization.

21679165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255071.

The product of its digits is 22680, while the sum is 37.

The square root of 21679165 is about 4656.0890240630. The cubic root of 21679165 is about 278.8351479640.

The spelling of 21679165 in words is "twenty-one million, six hundred seventy-nine thousand, one hundred sixty-five".