21156672 has 56 divisors (see below), whose sum is σ = 56583072. Its totient is φ = 6976000.

The previous prime is 21156661. The next prime is 21156701. The reversal of 21156672 is 27665112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18847 + ... + 19937.

It is an arithmetic number, because the mean of its divisors is an integer number (1010412).

Almost surely, 2^21156672 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 21156672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28291536).

21156672 is an abundant number, since it is smaller than the sum of its proper divisors (35426400).

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

21156672 is a wasteful number, since it uses less digits than its factorization.

21156672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1207 (or 1197 counting only the distinct ones).

The product of its digits is 5040, while the sum is 30.

The square root of 21156672 is about 4599.6382466451. The cubic root of 21156672 is about 276.5768234594.

The spelling of 21156672 in words is "twenty-one million, one hundred fifty-six thousand, six hundred seventy-two".