21680275 has 6 divisors (see below), whose sum is σ = 26883572. Its totient is φ = 17344200.

The previous prime is 21680257. The next prime is 21680279. The reversal of 21680275 is 57208612.

It is a de Polignac number, because none of the positive numbers 2^k-21680275 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21680279) 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 5 ways as a sum of consecutive naturals, for example, 433581 + ... + 433630.

Almost surely, 2^21680275 is an apocalyptic number.

21680275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21680275 is a deficient number, since it is larger than the sum of its proper divisors (5203297).

21680275 is an equidigital number, since it uses as much as digits as its factorization.

21680275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 867221 (or 867216 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 21680275 is about 4656.2082212891. The cubic root of 21680275 is about 278.8399067840.

Adding to 21680275 its reverse (57208612), we get a palindrome (78888887).

The spelling of 21680275 in words is "twenty-one million, six hundred eighty thousand, two hundred seventy-five".