21301056 has 140 divisors (see below), whose sum is σ = 72286368. Its totient is φ = 6075648.

The previous prime is 21301043. The next prime is 21301057. The reversal of 21301056 is 65010312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21301057) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 35995 + ... + 36581.

Almost surely, 2^21301056 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 21301056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36143184).

21301056 is an abundant number, since it is smaller than the sum of its proper divisors (50985312).

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

21301056 is an equidigital number, since it uses as much as digits as its factorization.

21301056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618 (or 599 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21301056 is about 4615.3067070348. The cubic root of 21301056 is about 277.2045650567.

Adding to 21301056 its reverse (65010312), we get a palindrome (86311368).

The spelling of 21301056 in words is "twenty-one million, three hundred one thousand, fifty-six".