21003000 has 64 divisors (see below), whose sum is σ = 65538720. Its totient is φ = 5600000.

The previous prime is 21002987. The next prime is 21003001. The reversal of 21003000 is 30012.

It is a super-2 number, since 2×21003000² = 882252018000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21003000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 501 + ... + 6500.

Almost surely, 2^21003000 is an apocalyptic number.

21003000 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 21003000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32769360).

21003000 is an abundant number, since it is smaller than the sum of its proper divisors (44535720).

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

21003000 is a wasteful number, since it uses less digits than its factorization.

21003000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7025 (or 7011 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 6.

The square root of 21003000 is about 4582.9030101018. The cubic root of 21003000 is about 275.9055547467.

Adding to 21003000 its reverse (30012), we get a palindrome (21033012).

The spelling of 21003000 in words is "twenty-one million, three thousand".