21003275 has 24 divisors (see below), whose sum is σ = 27581568. Its totient is φ = 15840000.

The previous prime is 21003271. The next prime is 21003293. The reversal of 21003275 is 57230012.

It is not a de Polignac number, because 21003275 - 2² = 21003271 is a prime.

It is a super-2 number, since 2×21003275² = 882275121451250, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21003271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31445 + ... + 32105.

It is an arithmetic number, because the mean of its divisors is an integer number (1149232).

Almost surely, 2^21003275 is an apocalyptic number.

21003275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21003275 is a deficient number, since it is larger than the sum of its proper divisors (6578293).

21003275 is a wasteful number, since it uses less digits than its factorization.

21003275 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 743 (or 738 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 21003275 is about 4582.9330128205. The cubic root of 21003275 is about 275.9067589191.

Adding to 21003275 its reverse (57230012), we get a palindrome (78233287).

The spelling of 21003275 in words is "twenty-one million, three thousand, two hundred seventy-five".