21075450 has 96 divisors (see below), whose sum is σ = 58335552. Its totient is φ = 4992000.

The previous prime is 21075437. The next prime is 21075451. The reversal of 21075450 is 5457012.

It is a self number, because there is not a number n which added to its sum of digits gives 21075450.

It is not an unprimeable number, because it can be changed into a prime (21075451) by changing a digit.

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, 87330 + ... + 87570.

It is an arithmetic number, because the mean of its divisors is an integer number (607662).

Almost surely, 2^21075450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21075450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29167776).

21075450 is an abundant number, since it is smaller than the sum of its proper divisors (37260102).

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

21075450 is a wasteful number, since it uses less digits than its factorization.

21075450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21075450 is about 4590.8005837762. The cubic root of 21075450 is about 276.2224367304. Note that the first 3 decimals are identical.

It can be divided in two parts, 2107 and 5450, that added together give a palindrome (7557).

The spelling of 21075450 in words is "twenty-one million, seventy-five thousand, four hundred fifty".