21328900 has 18 divisors (see below), whose sum is σ = 46283930. Its totient is φ = 8531520.

The previous prime is 21328873. The next prime is 21328907. The reversal of 21328900 is 982312.

It can be written as a sum of positive squares in 3 ways, for example, as 315844 + 21013056 = 562^2 + 4584^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21328907) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 106545 + ... + 106744.

Almost surely, 2^21328900 is an apocalyptic number.

21328900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21328900 is an abundant number, since it is smaller than the sum of its proper divisors (24955030).

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

21328900 is a wasteful number, since it uses less digits than its factorization.

21328900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213303 (or 213296 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21328900 is about 4618.3222061697. The cubic root of 21328900 is about 277.3252965240.

The spelling of 21328900 in words is "twenty-one million, three hundred twenty-eight thousand, nine hundred".