21003889 has 3 divisors (see below), whose sum is σ = 21008473. Its totient is φ = 20999306.

The previous prime is 21003887. The next prime is 21003893. The reversal of 21003889 is 98830012.

The square root of 21003889 is 4583.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 21003889 - 2¹ = 21003887 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21003889.

It is not an unprimeable number, because it can be changed into a prime (21003883) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2292 + ... + 6874.

Almost surely, 2^21003889 is an apocalyptic number.

21003889 is the 4583-rd square number.

21003889 is the 2292-nd centered octagonal number.

It is an amenable number.

21003889 is a deficient number, since it is larger than the sum of its proper divisors (4584).

21003889 is an frugal number, since it uses more digits than its factorization.

21003889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9166 (or 4583 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 31.

The cubic root of 21003889 is about 275.9094474696.

The spelling of 21003889 in words is "twenty-one million, three thousand, eight hundred eighty-nine".