21100530 has 64 divisors (see below), whose sum is σ = 56567808. Its totient is φ = 4992960.

The previous prime is 21100529. The next prime is 21100531. The reversal of 21100530 is 3500112.

It is an interprime number because it is at equal distance from previous prime (21100529) and next prime (21100531).

It is not an unprimeable number, because it can be changed into a prime (21100531) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13447 + ... + 14933.

It is an arithmetic number, because the mean of its divisors is an integer number (883872).

Almost surely, 2^21100530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21100530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28283904).

21100530 is an abundant number, since it is smaller than the sum of its proper divisors (35467278).

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

21100530 is a wasteful number, since it uses less digits than its factorization.

21100530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1551.

The product of its (nonzero) digits is 30, while the sum is 12.

The square root of 21100530 is about 4593.5313213257. The cubic root of 21100530 is about 276.3319624667.

Adding to 21100530 its reverse (3500112), we get a palindrome (24600642).

The spelling of 21100530 in words is "twenty-one million, one hundred thousand, five hundred thirty".