21118125 has 40 divisors (see below), whose sum is σ = 40237120. Its totient is φ = 9648000.

The previous prime is 21118103. The next prime is 21118129. The reversal of 21118125 is 52181112.

It is not a de Polignac number, because 21118125 - 2⁵ = 21118093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21118129) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 12321 + ... + 13929.

It is an arithmetic number, because the mean of its divisors is an integer number (1005928).

Almost surely, 2^21118125 is an apocalyptic number.

21118125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21118125 is a deficient number, since it is larger than the sum of its proper divisors (19118995).

21118125 is an equidigital number, since it uses as much as digits as its factorization.

21118125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639 (or 1624 counting only the distinct ones).

The product of its digits is 160, while the sum is 21.

The square root of 21118125 is about 4595.4461154495. The cubic root of 21118125 is about 276.4087490066.

Adding to 21118125 its reverse (52181112), we get a palindrome (73299237).

It can be divided in two parts, 211 and 18125, that added together give a triangular number (18336 = T₁₉₁).

The spelling of 21118125 in words is "twenty-one million, one hundred eighteen thousand, one hundred twenty-five".