21591296 has 72 divisors (see below), whose sum is σ = 47584320. Its totient is φ = 9732096.

The previous prime is 21591293. The next prime is 21591307. The reversal of 21591296 is 69219512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21591293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 111776 + ... + 111968.

Almost surely, 2^21591296 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 21591296, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23792160).

21591296 is an abundant number, since it is smaller than the sum of its proper divisors (25993024).

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

21591296 is a wasteful number, since it uses less digits than its factorization.

21591296 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 251 (or 237 counting only the distinct ones).

The product of its digits is 9720, while the sum is 35.

The square root of 21591296 is about 4646.6435197893. The cubic root of 21591296 is about 278.4579172232.

It can be divided in two parts, 21591 and 296, that multiplied together give a palindrome (6390936).

The spelling of 21591296 in words is "twenty-one million, five hundred ninety-one thousand, two hundred ninety-six".