21116225 has 24 divisors (see below), whose sum is σ = 28873152. Its totient is φ = 15220800.

The previous prime is 21116219. The next prime is 21116257. The reversal of 21116225 is 52261112.

It is not a de Polignac number, because 21116225 - 2⁴ = 21116209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21116197 and 21116206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13220 + ... + 14730.

It is an arithmetic number, because the mean of its divisors is an integer number (1203048).

Almost surely, 2^21116225 is an apocalyptic number.

21116225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21116225 is a deficient number, since it is larger than the sum of its proper divisors (7756927).

21116225 is a wasteful number, since it uses less digits than its factorization.

21116225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1577 (or 1572 counting only the distinct ones).

The product of its digits is 240, while the sum is 20.

The square root of 21116225 is about 4595.2393844064. The cubic root of 21116225 is about 276.4004592496.

Adding to 21116225 its reverse (52261112), we get a palindrome (73377337).

The spelling of 21116225 in words is "twenty-one million, one hundred sixteen thousand, two hundred twenty-five".