21751033 has 4 divisors (see below), whose sum is σ = 22281588. Its totient is φ = 21220480.

The previous prime is 21751027. The next prime is 21751039. The reversal of 21751033 is 33015712.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21751027) and next prime (21751039).

It can be written as a sum of positive squares in 2 ways, for example, as 12588304 + 9162729 = 3548^2 + 3027^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21751033 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21750995 and 21751013.

It is not an unprimeable number, because it can be changed into a prime (21751039) 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, 265216 + ... + 265297.

It is an arithmetic number, because the mean of its divisors is an integer number (5570397).

Almost surely, 2^21751033 is an apocalyptic number.

It is an amenable number.

21751033 is a deficient number, since it is larger than the sum of its proper divisors (530555).

21751033 is an equidigital number, since it uses as much as digits as its factorization.

21751033 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530554.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21751033 is about 4663.8002744543. The cubic root of 21751033 is about 279.1429276713.

Adding to 21751033 its reverse (33015712), we get a palindrome (54766745).

The spelling of 21751033 in words is "twenty-one million, seven hundred fifty-one thousand, thirty-three".