21030750 has 96 divisors (see below), whose sum is σ = 61326720. Its totient is φ = 5169600.

The previous prime is 21030721. The next prime is 21030767. The reversal of 21030750 is 5703012.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28891 + ... + 29609.

It is an arithmetic number, because the mean of its divisors is an integer number (638820).

Almost surely, 2^21030750 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21030750, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30663360).

21030750 is an abundant number, since it is smaller than the sum of its proper divisors (40295970).

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

21030750 is a wasteful number, since it uses less digits than its factorization.

21030750 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755 (or 742 counting only the distinct ones).

The product of its (nonzero) digits is 210, while the sum is 18.

The square root of 21030750 is about 4585.9295677103. The cubic root of 21030750 is about 276.0270137390.

Adding to 21030750 its reverse (5703012), we get a palindrome (26733762).

The spelling of 21030750 in words is "twenty-one million, thirty thousand, seven hundred fifty".