21857268 has 24 divisors (see below), whose sum is σ = 53218368. Its totient is φ = 6968896.

The previous prime is 21857233. The next prime is 21857273. The reversal of 21857268 is 86275812.

It is a hoax number, since the sum of its digits (39) 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 (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39321 + ... + 39872.

It is an arithmetic number, because the mean of its divisors is an integer number (2217432).

Almost surely, 2^21857268 is an apocalyptic number.

It is an amenable number.

21857268 is an abundant number, since it is smaller than the sum of its proper divisors (31361100).

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

21857268 is a wasteful number, since it uses less digits than its factorization.

21857268 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79223 (or 79221 counting only the distinct ones).

The product of its digits is 53760, while the sum is 39.

The square root of 21857268 is about 4675.1757186228. The cubic root of 21857268 is about 279.5966471218.

It can be divided in two parts, 2185 and 7268, that added together give a triangular number (9453 = T₁₃₇).

The spelling of 21857268 in words is "twenty-one million, eight hundred fifty-seven thousand, two hundred sixty-eight".