21172284 has 36 divisors (see below), whose sum is σ = 61165104. Its totient is φ = 6049152.

The previous prime is 21172273. The next prime is 21172309. The reversal of 21172284 is 48227112.

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41757 + ... + 42260.

Almost surely, 2^21172284 is an apocalyptic number.

It is an amenable number.

21172284 is an abundant number, since it is smaller than the sum of its proper divisors (39992820).

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

21172284 is a wasteful number, since it uses less digits than its factorization.

21172284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84034 (or 84029 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21172284 is about 4601.3350236643. The cubic root of 21172284 is about 276.6448375545.

Adding to 21172284 its reverse (48227112), we get a palindrome (69399396).

The spelling of 21172284 in words is "twenty-one million, one hundred seventy-two thousand, two hundred eighty-four".