21213800 has 48 divisors (see below), whose sum is σ = 50032140. Its totient is φ = 8363520.

The previous prime is 21213799. The next prime is 21213809. The reversal of 21213800 is 831212.

It can be written as a sum of positive squares in 6 ways, for example, as 14853316 + 6360484 = 3854^2 + 2522^2 .

It is not an unprimeable number, because it can be changed into a prime (21213809) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 13874 + ... + 15326.

Almost surely, 2^21213800 is an apocalyptic number.

21213800 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 21213800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25016070).

21213800 is an abundant number, since it is smaller than the sum of its proper divisors (28818340).

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

21213800 is a wasteful number, since it uses less digits than its factorization.

21213800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1542 (or 1533 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21213800 is about 4605.8441137320. The cubic root of 21213800 is about 276.8255405949.

The spelling of 21213800 in words is "twenty-one million, two hundred thirteen thousand, eight hundred".