21180672 has 108 divisors (see below), whose sum is σ = 63374220. Its totient is φ = 6795264.

The previous prime is 21180667. The next prime is 21180683. The reversal of 21180672 is 27608112.

It can be written as a sum of positive squares in 2 ways, for example, as 5308416 + 15872256 = 2304^2 + 3984^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 66658 + ... + 66974.

Almost surely, 2^21180672 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21180672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31687110).

21180672 is an abundant number, since it is smaller than the sum of its proper divisors (42193548).

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

21180672 is a wasteful number, since it uses less digits than its factorization.

21180672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368 (or 351 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21180672 is about 4602.2464080056. The cubic root of 21180672 is about 276.6813662937.

Adding to 21180672 its reverse (27608112), we get a palindrome (48788784).

The spelling of 21180672 in words is "twenty-one million, one hundred eighty thousand, six hundred seventy-two".