21116825 has 18 divisors (see below), whose sum is σ = 26955306. Its totient is φ = 16410240.

The previous prime is 21116819. The next prime is 21116831. The reversal of 21116825 is 52861112.

It is an interprime number because it is at equal distance from previous prime (21116819) and next prime (21116831).

It can be written as a sum of positive squares in 9 ways, for example, as 3003289 + 18113536 = 1733^2 + 4256^2 .

It is not a de Polignac number, because 21116825 - 2⁶ = 21116761 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21116794 and 21116803.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 33917 + ... + 34533.

It is an arithmetic number, because the mean of its divisors is an integer number (1497517).

Almost surely, 2^21116825 is an apocalyptic number.

21116825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21116825 is a deficient number, since it is larger than the sum of its proper divisors (5838481).

21116825 is an equidigital number, since it uses as much as digits as its factorization.

21116825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 701 (or 659 counting only the distinct ones).

The product of its digits is 960, while the sum is 26.

The square root of 21116825 is about 4595.3046688985. The cubic root of 21116825 is about 276.4030771213.

Adding to 21116825 its reverse (52861112), we get a palindrome (73977937).

The spelling of 21116825 in words is "twenty-one million, one hundred sixteen thousand, eight hundred twenty-five".