21003331 has 2 divisors, whose sum is σ = 21003332. Its totient is φ = 21003330.

The previous prime is 21003329. The next prime is 21003343. The reversal of 21003331 is 13330012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21003331 - 2¹ = 21003329 is a prime.

It is a super-2 number, since 2×21003331² = 882279826191122, which contains 22 as substring.

Together with 21003329, it forms a pair of twin primes.

It is equal to p_1330150 and since 21003331 and 1330150 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21003371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501665 + 10501666.

It is an arithmetic number, because the mean of its divisors is an integer number (10501666).

Almost surely, 2^21003331 is an apocalyptic number.

21003331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003331 is an equidigital number, since it uses as much as digits as its factorization.

21003331 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54, while the sum is 13.

The square root of 21003331 is about 4582.9391224410. The cubic root of 21003331 is about 275.9070041311.

Adding to 21003331 its reverse (13330012), we get a palindrome (34333343).

The spelling of 21003331 in words is "twenty-one million, three thousand, three hundred thirty-one".