21045125 has 16 divisors (see below), whose sum is σ = 27116544. Its totient is φ = 16290000.

The previous prime is 21045109. The next prime is 21045127. The reversal of 21045125 is 52154012.

It is not a de Polignac number, because 21045125 - 2⁴ = 21045109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21045097 and 21045106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1160 + ... + 6590.

It is an arithmetic number, because the mean of its divisors is an integer number (1694784).

Almost surely, 2^21045125 is an apocalyptic number.

21045125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21045125 is a deficient number, since it is larger than the sum of its proper divisors (6071419).

21045125 is an equidigital number, since it uses as much as digits as its factorization.

21045125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5477 (or 5467 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21045125 is about 4587.4965940042. The cubic root of 21045125 is about 276.0898896805.

Adding to 21045125 its reverse (52154012), we get a palindrome (73199137).

The spelling of 21045125 in words is "twenty-one million, forty-five thousand, one hundred twenty-five".