20721300 has 108 divisors (see below), whose sum is σ = 63954240. Its totient is φ = 5178880.

The previous prime is 20721293. The next prime is 20721301. The reversal of 20721300 is 312702.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 20721300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20721301) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 86581 + ... + 86819.

Almost surely, 2^20721300 is an apocalyptic number.

20721300 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 20721300, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31977120).

20721300 is an abundant number, since it is smaller than the sum of its proper divisors (43232940).

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

20721300 is a wasteful number, since it uses less digits than its factorization.

20721300 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 20721300 is about 4552.0654652586. The cubic root of 20721300 is about 274.6664827294. Note that the first 3 decimals are identical.

The spelling of 20721300 in words is "twenty million, seven hundred twenty-one thousand, three hundred".