21001300 has 54 divisors (see below), whose sum is σ = 47760398. Its totient is φ = 8015040.

The previous prime is 21001247. The next prime is 21001319. The reversal of 21001300 is 310012.

It can be written as a sum of positive squares in 3 ways, for example, as 2304324 + 18696976 = 1518^2 + 4324^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 52702 + ... + 53098.

Almost surely, 2^21001300 is an apocalyptic number.

21001300 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 21001300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23880199).

21001300 is an abundant number, since it is smaller than the sum of its proper divisors (26759098).

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

21001300 is a wasteful number, since it uses less digits than its factorization.

21001300 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457 (or 427 counting only the distinct ones).

The product of its (nonzero) digits is 6, while the sum is 7.

The square root of 21001300 is about 4582.7175343894. The cubic root of 21001300 is about 275.8981105388.

Adding to 21001300 its reverse (310012), we get a palindrome (21311312).

The spelling of 21001300 in words is "twenty-one million, one thousand, three hundred".