21197312 has 40 divisors (see below), whose sum is σ = 44602800. Its totient is φ = 10036224.

The previous prime is 21197311. The next prime is 21197321. The reversal of 21197312 is 21379112.

It is not an unprimeable number, because it can be changed into a prime (21197311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8639 + ... + 10817.

It is an arithmetic number, because the mean of its divisors is an integer number (1115070).

Almost surely, 2^21197312 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 21197312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22301400).

21197312 is an abundant number, since it is smaller than the sum of its proper divisors (23405488).

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

21197312 is an equidigital number, since it uses as much as digits as its factorization.

21197312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2216 (or 2200 counting only the distinct ones).

The product of its digits is 756, while the sum is 26.

The square root of 21197312 is about 4604.0538658882. The cubic root of 21197312 is about 276.7538029756.

The spelling of 21197312 in words is "twenty-one million, one hundred ninety-seven thousand, three hundred twelve".