21080275 has 6 divisors (see below), whose sum is σ = 26139572. Its totient is φ = 16864200.

The previous prime is 21080261. The next prime is 21080317. The reversal of 21080275 is 57208012.

It is a de Polignac number, because none of the positive numbers 2^k-21080275 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 843211 = 21080275 / (2 + 1 + 0 + 8 + 0 + 2 + 7 + 5).

It is a Duffinian number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 421581 + ... + 421630.

Almost surely, 2^21080275 is an apocalyptic number.

21080275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21080275 is a deficient number, since it is larger than the sum of its proper divisors (5059297).

21080275 is an equidigital number, since it uses as much as digits as its factorization.

21080275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 843221 (or 843216 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21080275 is about 4591.3260611723. The cubic root of 21080275 is about 276.2435145178.

Adding to 21080275 its reverse (57208012), we get a palindrome (78288287).

The spelling of 21080275 in words is "twenty-one million, eighty thousand, two hundred seventy-five".