21075900 has 72 divisors (see below), whose sum is σ = 61496064. Its totient is φ = 5572800.

The previous prime is 21075871. The next prime is 21075907. The reversal of 21075900 is 957012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075907) 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 23 ways as a sum of consecutive naturals, for example, 48685 + ... + 49115.

It is an arithmetic number, because the mean of its divisors is an integer number (854112).

Almost surely, 2^21075900 is an apocalyptic number.

21075900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21075900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30748032).

21075900 is an abundant number, since it is smaller than the sum of its proper divisors (40420164).

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

21075900 is a wasteful number, since it uses less digits than its factorization.

21075900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611 (or 604 counting only the distinct ones).

The product of its (nonzero) digits is 630, while the sum is 24.

The square root of 21075900 is about 4590.8495945740. The cubic root of 21075900 is about 276.2244026704.

The spelling of 21075900 in words is "twenty-one million, seventy-five thousand, nine hundred".