21665170 has 16 divisors (see below), whose sum is σ = 39087360. Its totient is φ = 8646064.

The previous prime is 21665143. The next prime is 21665183. The reversal of 21665170 is 7156612.

It is a super-2 number, since 2×21665170² = 938759182257800, which contains 22 as substring.

It is an unprimeable number.

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, 2529 + ... + 7051.

It is an arithmetic number, because the mean of its divisors is an integer number (2442960).

Almost surely, 2^21665170 is an apocalyptic number.

21665170 is a deficient number, since it is larger than the sum of its proper divisors (17422190).

21665170 is a wasteful number, since it uses less digits than its factorization.

21665170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5009.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21665170 is about 4654.5859106907. The cubic root of 21665170 is about 278.7751343072.

The spelling of 21665170 in words is "twenty-one million, six hundred sixty-five thousand, one hundred seventy".