21309166 has 8 divisors (see below), whose sum is σ = 32707224. Its totient is φ = 10406760.

The previous prime is 21309133. The next prime is 21309179. The reversal of 21309166 is 66190312.

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

It is a congruent 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 in 3 ways as a sum of consecutive naturals, for example, 123805 + ... + 123976.

It is an arithmetic number, because the mean of its divisors is an integer number (4088403).

Almost surely, 2^21309166 is an apocalyptic number.

21309166 is a deficient number, since it is larger than the sum of its proper divisors (11398058).

21309166 is a wasteful number, since it uses less digits than its factorization.

21309166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247826.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21309166 is about 4616.1852215872. The cubic root of 21309166 is about 277.2397408365.

Adding to 21309166 its reverse (66190312), we get a palindrome (87499478).

The spelling of 21309166 in words is "twenty-one million, three hundred nine thousand, one hundred sixty-six".