21043000 has 64 divisors (see below), whose sum is σ = 53745120. Its totient is φ = 7648000.

The previous prime is 21042997. The next prime is 21043007. The reversal of 21043000 is 34012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21043007) 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, 10044 + ... + 11956.

Almost surely, 2^21043000 is an apocalyptic number.

21043000 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 21043000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26872560).

21043000 is an abundant number, since it is smaller than the sum of its proper divisors (32702120).

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

21043000 is a wasteful number, since it uses less digits than its factorization.

21043000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1945 (or 1931 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 10.

The square root of 21043000 is about 4587.2649803559. The cubic root of 21043000 is about 276.0805967799.

Adding to 21043000 its reverse (34012), we get a palindrome (21077012).

The spelling of 21043000 in words is "twenty-one million, forty-three thousand".