21125056 has 28 divisors (see below), whose sum is σ = 42519600. Its totient is φ = 10411520.

The previous prime is 21125029. The next prime is 21125057. The reversal of 21125056 is 65052112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125057) 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, 2220 + ... + 6868.

Almost surely, 2^21125056 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 21125056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21259800).

21125056 is an abundant number, since it is smaller than the sum of its proper divisors (21394544).

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

21125056 is an equidigital number, since it uses as much as digits as its factorization.

21125056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4732 (or 4722 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 21125056 is about 4596.2001697054. The cubic root of 21125056 is about 276.4389849531.

Adding to 21125056 its reverse (65052112), we get a palindrome (86177168).

The spelling of 21125056 in words is "twenty-one million, one hundred twenty-five thousand, fifty-six".