21171284 has 12 divisors (see below), whose sum is σ = 37118004. Its totient is φ = 10566144.

The previous prime is 21171253. The next prime is 21171313. The reversal of 21171284 is 48217112.

It can be written as a sum of positive squares in 2 ways, for example, as 11424400 + 9746884 = 3380^2 + 3122^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2279 + ... + 6894.

It is an arithmetic number, because the mean of its divisors is an integer number (3093167).

Almost surely, 2^21171284 is an apocalyptic number.

It is an amenable number.

21171284 is a deficient number, since it is larger than the sum of its proper divisors (15946720).

21171284 is a wasteful number, since it uses less digits than its factorization.

21171284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9754 (or 9752 counting only the distinct ones).

The product of its digits is 896, while the sum is 26.

The square root of 21171284 is about 4601.2263582658. The cubic root of 21171284 is about 276.6404820302.

Adding to 21171284 its reverse (48217112), we get a palindrome (69388396).

The spelling of 21171284 in words is "twenty-one million, one hundred seventy-one thousand, two hundred eighty-four".