21003316 has 24 divisors (see below), whose sum is σ = 38130624. Its totient is φ = 10115520.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003316 is 61330012.

It is a super-2 number, since 2×21003316² = 882278565991712, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21003316.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12841 + ... + 14383.

It is an arithmetic number, because the mean of its divisors is an integer number (1588776).

Almost surely, 2^21003316 is an apocalyptic number.

It is an amenable number.

21003316 is a deficient number, since it is larger than the sum of its proper divisors (17127308).

21003316 is a wasteful number, since it uses less digits than its factorization.

21003316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1671 (or 1669 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 16.

The square root of 21003316 is about 4582.9374859363. The cubic root of 21003316 is about 275.9069384493.

Adding to 21003316 its reverse (61330012), we get a palindrome (82333328).

It can be divided in two parts, 210033 and 16, that multiplied together give a triangular number (3360528 = T₂₅₉₂).

The spelling of 21003316 in words is "twenty-one million, three thousand, three hundred sixteen".