21678272 has 112 divisors (see below), whose sum is σ = 55302912. Its totient is φ = 8186880.

The previous prime is 21678257. The next prime is 21678277. The reversal of 21678272 is 27287612.

It is a tau number, because it is divible by the number of its divisors (112).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678277) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 261143 + ... + 261225.

It is an arithmetic number, because the mean of its divisors is an integer number (493776).

Almost surely, 2^21678272 is an apocalyptic number.

21678272 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21678272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27651456).

21678272 is an abundant number, since it is smaller than the sum of its proper divisors (33624640).

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

21678272 is a wasteful number, since it uses less digits than its factorization.

21678272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166 (or 156 counting only the distinct ones).

The product of its digits is 18816, while the sum is 35.

The square root of 21678272 is about 4655.9931271427. The cubic root of 21678272 is about 278.8313193540.

The spelling of 21678272 in words is "twenty-one million, six hundred seventy-eight thousand, two hundred seventy-two".