21391296 has 56 divisors (see below), whose sum is σ = 57936384. Its totient is φ = 6961920.

The previous prime is 21391267. The next prime is 21391301. The reversal of 21391296 is 69219312.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 6961 + ... + 9551.

Almost surely, 2^21391296 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 21391296, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28968192).

21391296 is an abundant number, since it is smaller than the sum of its proper divisors (36545088).

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

21391296 is a wasteful number, since it uses less digits than its factorization.

21391296 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2649 (or 2639 counting only the distinct ones).

The product of its digits is 5832, while the sum is 33.

The square root of 21391296 is about 4625.0725399717. The cubic root of 21391296 is about 277.5954642738.

The spelling of 21391296 in words is "twenty-one million, three hundred ninety-one thousand, two hundred ninety-six".