21309168 has 20 divisors (see below), whose sum is σ = 55048808. Its totient is φ = 7103040.

The previous prime is 21309133. The next prime is 21309179. The reversal of 21309168 is 86190312.

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 221923 + ... + 222018.

Almost surely, 2^21309168 is an apocalyptic number.

It is an amenable number.

21309168 is an abundant number, since it is smaller than the sum of its proper divisors (33739640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21309168 is a wasteful number, since it uses less digits than its factorization.

21309168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 443952 (or 443946 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 21309168 is about 4616.1854382163. The cubic root of 21309168 is about 277.2397495101.

The spelling of 21309168 in words is "twenty-one million, three hundred nine thousand, one hundred sixty-eight".