21016900 has 18 divisors (see below), whose sum is σ = 45606890. Its totient is φ = 8406720.

The previous prime is 21016883. The next prime is 21016901. The reversal of 21016900 is 961012.

It can be written as a sum of positive squares in 3 ways, for example, as 3844 + 21013056 = 62^2 + 4584^2 .

It is a super-2 number, since 2×21016900² = 883420171220000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21016901) 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, 104985 + ... + 105184.

Almost surely, 2^21016900 is an apocalyptic number.

21016900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21016900 is an abundant number, since it is smaller than the sum of its proper divisors (24589990).

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

21016900 is a wasteful number, since it uses less digits than its factorization.

21016900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210183 (or 210176 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 21016900 is about 4584.4192652941. The cubic root of 21016900 is about 275.9664070296.

Adding to 21016900 its reverse (961012), we get a palindrome (21977912).

The spelling of 21016900 in words is "twenty-one million, sixteen thousand, nine hundred".