21497056 has 48 divisors (see below), whose sum is σ = 50924160. Its totient is φ = 8726400.

The previous prime is 21497053. The next prime is 21497057. The reversal of 21497056 is 65079412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21497053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1731 + ... + 6781.

It is an arithmetic number, because the mean of its divisors is an integer number (1060920).

Almost surely, 2^21497056 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 21497056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25462080).

21497056 is an abundant number, since it is smaller than the sum of its proper divisors (29427104).

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

21497056 is a wasteful number, since it uses less digits than its factorization.

21497056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5087 (or 5079 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 21497056 is about 4636.4917771953. The cubic root of 21497056 is about 278.0521959168.

The spelling of 21497056 in words is "twenty-one million, four hundred ninety-seven thousand, fifty-six".