21125075 has 6 divisors (see below), whose sum is σ = 26195124. Its totient is φ = 16900040.

The previous prime is 21125057. The next prime is 21125087. The reversal of 21125075 is 57052112.

It is a happy number.

It is not a de Polignac number, because 21125075 - 2⁸ = 21124819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21125075.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 422477 + ... + 422526.

It is an arithmetic number, because the mean of its divisors is an integer number (4365854).

Almost surely, 2^21125075 is an apocalyptic number.

21125075 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21125075 is a deficient number, since it is larger than the sum of its proper divisors (5070049).

21125075 is an equidigital number, since it uses as much as digits as its factorization.

21125075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845013 (or 845008 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21125075 is about 4596.2022366297. The cubic root of 21125075 is about 276.4390678300.

Adding to 21125075 its reverse (57052112), we get a palindrome (78177187).

The spelling of 21125075 in words is "twenty-one million, one hundred twenty-five thousand, seventy-five".