21275233 has 4 divisors (see below), whose sum is σ = 24314560. Its totient is φ = 18235908.

The previous prime is 21275209. The next prime is 21275237. The reversal of 21275233 is 33257212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21275233 - 2¹³ = 21267041 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21275198 and 21275207.

It is not an unprimeable number, because it can be changed into a prime (21275237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1519653 + ... + 1519666.

It is an arithmetic number, because the mean of its divisors is an integer number (6078640).

Almost surely, 2^21275233 is an apocalyptic number.

It is an amenable number.

21275233 is a deficient number, since it is larger than the sum of its proper divisors (3039327).

21275233 is an equidigital number, since it uses as much as digits as its factorization.

21275233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3039326.

The product of its digits is 2520, while the sum is 25.

The square root of 21275233 is about 4612.5083197757. The cubic root of 21275233 is about 277.0925025678.

The spelling of 21275233 in words is "twenty-one million, two hundred seventy-five thousand, two hundred thirty-three".