21003313 has 16 divisors (see below), whose sum is σ = 23030784. Its totient is φ = 19077120.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003313 is 31330012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21003313 is a prime.

It is a super-2 number, since 2×21003313² = 882278313951938, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21003293 and 21003302.

It is not an unprimeable number, because it can be changed into a prime (21003343) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77368 + ... + 77638.

It is an arithmetic number, because the mean of its divisors is an integer number (1439424).

Almost surely, 2^21003313 is an apocalyptic number.

It is an amenable number.

21003313 is a deficient number, since it is larger than the sum of its proper divisors (2027471).

21003313 is a wasteful number, since it uses less digits than its factorization.

21003313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432.

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

The square root of 21003313 is about 4582.9371586353. The cubic root of 21003313 is about 275.9069253130.

Adding to 21003313 its reverse (31330012), we get a palindrome (52333325).

It can be divided in two parts, 21003 and 313, that added together give a square (21316 = 146²).

The spelling of 21003313 in words is "twenty-one million, three thousand, three hundred thirteen".