21003315 has 16 divisors (see below), whose sum is σ = 33785856. Its totient is φ = 11141600.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003315 is 51330012.

It is a happy number.

It is not a de Polignac number, because 21003315 - 2⁴ = 21003299 is a prime.

It is a super-2 number, since 2×21003315² = 882278481978450, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a junction number, because it is equal to n+sod(n) for n = 21003294 and 21003303.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 801 + ... + 6530.

It is an arithmetic number, because the mean of its divisors is an integer number (2111616).

Almost surely, 2^21003315 is an apocalyptic number.

21003315 is a deficient number, since it is larger than the sum of its proper divisors (12782541).

21003315 is a wasteful number, since it uses less digits than its factorization.

21003315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7530.

The product of its (nonzero) digits is 90, while the sum is 15.

The square root of 21003315 is about 4582.9373768360. The cubic root of 21003315 is about 275.9069340706.

Adding to 21003315 its reverse (51330012), we get a palindrome (72333327).

The spelling of 21003315 in words is "twenty-one million, three thousand, three hundred fifteen".