21003311 has 6 divisors (see below), whose sum is σ = 24432480. Its totient is φ = 18002796.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003311 is 11330012.

It is not a de Polignac number, because 21003311 - 2⁶ = 21003247 is a prime.

It is a super-2 number, since 2×21003311² = 882278145925442, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21003292 and 21003301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21003331) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 214271 + ... + 214368.

It is an arithmetic number, because the mean of its divisors is an integer number (4072080).

Almost surely, 2^21003311 is an apocalyptic number.

21003311 is a deficient number, since it is larger than the sum of its proper divisors (3429169).

21003311 is an equidigital number, since it uses as much as digits as its factorization.

21003311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 428653 (or 428646 counting only the distinct ones).

The product of its (nonzero) digits is 18, while the sum is 11.

The square root of 21003311 is about 4582.9369404346. The cubic root of 21003311 is about 275.9069165554.

Adding to 21003311 its reverse (11330012), we get a palindrome (32333323).

The spelling of 21003311 in words is "twenty-one million, three thousand, three hundred eleven".