21666170 has 16 divisors (see below), whose sum is σ = 39076128. Its totient is φ = 8649360.

The previous prime is 21666167. The next prime is 21666191. The reversal of 21666170 is 7166612.

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 in 7 ways as a sum of consecutive naturals, for example, 4025 + ... + 7715.

It is an arithmetic number, because the mean of its divisors is an integer number (2442258).

Almost surely, 2^21666170 is an apocalyptic number.

21666170 is a deficient number, since it is larger than the sum of its proper divisors (17409958).

21666170 is a wasteful number, since it uses less digits than its factorization.

21666170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4285.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 21666170 is about 4654.6933303925. The cubic root of 21666170 is about 278.7794233857.

The spelling of 21666170 in words is "twenty-one million, six hundred sixty-six thousand, one hundred seventy".