21051000 has 96 divisors (see below), whose sum is σ = 71182800. Its totient is φ = 5611200.

The previous prime is 21050987. The next prime is 21051011. The reversal of 21051000 is 15012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7831 + ... + 10169.

Almost surely, 2^21051000 is an apocalyptic number.

21051000 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 21051000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35591400).

21051000 is an abundant number, since it is smaller than the sum of its proper divisors (50131800).

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

21051000 is a wasteful number, since it uses less digits than its factorization.

21051000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2366 (or 2349 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 9.

The square root of 21051000 is about 4588.1368767725. The cubic root of 21051000 is about 276.1155785624.

Adding to 21051000 its reverse (15012), we get a palindrome (21066012).

The spelling of 21051000 in words is "twenty-one million, fifty-one thousand".