21116500 has 48 divisors (see below), whose sum is σ = 46584720. Its totient is φ = 8361600.

The previous prime is 21116479. The next prime is 21116503. The reversal of 21116500 is 561112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 14470416 + 6646084 = 3804^2 + 2578^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78366 + ... + 78634.

It is an arithmetic number, because the mean of its divisors is an integer number (970515).

Almost surely, 2^21116500 is an apocalyptic number.

21116500 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 21116500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23292360).

21116500 is an abundant number, since it is smaller than the sum of its proper divisors (25468220).

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

21116500 is a wasteful number, since it uses less digits than its factorization.

21116500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445 (or 433 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 21116500 is about 4595.2693065804. The cubic root of 21116500 is about 276.4016591137.

Adding to 21116500 its reverse (561112), we get a palindrome (21677612).

The spelling of 21116500 in words is "twenty-one million, one hundred sixteen thousand, five hundred".