21297204 has 72 divisors (see below), whose sum is σ = 56504448. Its totient is φ = 6756480.

The previous prime is 21297203. The next prime is 21297247. The reversal of 21297204 is 40279212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21297203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 69219 + ... + 69525.

It is an arithmetic number, because the mean of its divisors is an integer number (784784).

Almost surely, 2^21297204 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 21297204, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28252224).

21297204 is an abundant number, since it is smaller than the sum of its proper divisors (35207244).

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

21297204 is a wasteful number, since it uses less digits than its factorization.

21297204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405 (or 400 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21297204 is about 4614.8893811228. The cubic root of 21297204 is about 277.1878545180.

The spelling of 21297204 in words is "twenty-one million, two hundred ninety-seven thousand, two hundred four".