21171275 has 6 divisors (see below), whose sum is σ = 26252412. Its totient is φ = 16937000.

The previous prime is 21171253. The next prime is 21171313. The reversal of 21171275 is 57217112.

It is not a de Polignac number, because 21171275 - 2¹⁰ = 21170251 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 423401 + ... + 423450.

It is an arithmetic number, because the mean of its divisors is an integer number (4375402).

Almost surely, 2^21171275 is an apocalyptic number.

21171275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21171275 is a deficient number, since it is larger than the sum of its proper divisors (5081137).

21171275 is an equidigital number, since it uses as much as digits as its factorization.

21171275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846861 (or 846856 counting only the distinct ones).

The product of its digits is 980, while the sum is 26.

The square root of 21171275 is about 4601.2253802656. The cubic root of 21171275 is about 276.6404428299.

Adding to 21171275 its reverse (57217112), we get a palindrome (78388387).

The spelling of 21171275 in words is "twenty-one million, one hundred seventy-one thousand, two hundred seventy-five".